feat: add external metadata sync system with multiple providers

Add a complete metadata synchronization system allowing users to search
and sync series/book metadata from external providers (Google Books,
Open Library, ComicVine, AniList, Bédéthèque). Each library can use a
different provider. Matching requires manual approval with detailed sync
reports showing what was updated or skipped (locked fields protection).

Key changes:
- DB migrations: external_metadata_links, external_book_metadata tables,
  library metadata_provider column, locked_fields, total_volumes, book
  metadata fields (summary, isbn, publish_date)
- Rust API: MetadataProvider trait + 5 provider implementations,
  7 metadata endpoints (search, match, approve, reject, links, missing,
  delete), sync report system, provider language preference support
- Backoffice: MetadataSearchModal, ProviderIcon, SafeHtml components,
  settings UI for provider/language config, enriched book detail page,
  edit forms with locked fields support, API proxy routes
- OpenAPI/Swagger documentation for all new endpoints and schemas

Closes #3

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

apps/api/src/metadata_providers/open_library.rs

@@ -0,0 +1,351 @@
+use super::{BookCandidate, MetadataProvider, ProviderConfig, SeriesCandidate};
+
+pub struct OpenLibraryProvider;
+
+impl MetadataProvider for OpenLibraryProvider {
+    fn name(&self) -> &str {
+        "open_library"
+    }
+
+    fn search_series(
+        &self,
+        query: &str,
+        config: &ProviderConfig,
+    ) -> std::pin::Pin<
+        Box<dyn std::future::Future<Output = Result<Vec<SeriesCandidate>, String>> + Send + '_>,
+    > {
+        let query = query.to_string();
+        let config = config.clone();
+        Box::pin(async move { search_series_impl(&query, &config).await })
+    }
+
+    fn get_series_books(
+        &self,
+        external_id: &str,
+        config: &ProviderConfig,
+    ) -> std::pin::Pin<
+        Box<dyn std::future::Future<Output = Result<Vec<BookCandidate>, String>> + Send + '_>,
+    > {
+        let external_id = external_id.to_string();
+        let config = config.clone();
+        Box::pin(async move { get_series_books_impl(&external_id, &config).await })
+    }
+}
+
+async fn search_series_impl(
+    query: &str,
+    config: &ProviderConfig,
+) -> Result<Vec<SeriesCandidate>, String> {
+    let client = reqwest::Client::builder()
+        .timeout(std::time::Duration::from_secs(15))
+        .build()
+        .map_err(|e| format!("failed to build HTTP client: {e}"))?;
+
+    // Open Library uses 3-letter language codes
+    let ol_lang = match config.language.as_str() {
+        "fr" => "fre",
+        "es" => "spa",
+        _ => "eng",
+    };
+
+    let url = format!(
+        "https://openlibrary.org/search.json?title={}&limit=20&language={}",
+        urlencoded(query),
+        ol_lang,
+    );
+
+    let resp = client
+        .get(&url)
+        .send()
+        .await
+        .map_err(|e| format!("Open Library request failed: {e}"))?;
+
+    if !resp.status().is_success() {
+        let status = resp.status();
+        let text = resp.text().await.unwrap_or_default();
+        return Err(format!("Open Library returned {status}: {text}"));
+    }
+
+    let data: serde_json::Value = resp
+        .json()
+        .await
+        .map_err(|e| format!("Failed to parse Open Library response: {e}"))?;
+
+    let docs = match data.get("docs").and_then(|d| d.as_array()) {
+        Some(docs) => docs,
+        None => return Ok(vec![]),
+    };
+
+    let query_lower = query.to_lowercase();
+    let mut series_map: std::collections::HashMap<String, SeriesCandidateBuilder> =
+        std::collections::HashMap::new();
+
+    for doc in docs {
+        let title = doc
+            .get("title")
+            .and_then(|t| t.as_str())
+            .unwrap_or("")
+            .to_string();
+        let authors: Vec<String> = doc
+            .get("author_name")
+            .and_then(|a| a.as_array())
+            .map(|arr| arr.iter().filter_map(|v| v.as_str().map(String::from)).collect())
+            .unwrap_or_default();
+        let publishers: Vec<String> = doc
+            .get("publisher")
+            .and_then(|a| a.as_array())
+            .map(|arr| {
+                let mut pubs: Vec<String> = arr.iter().filter_map(|v| v.as_str().map(String::from)).collect();
+                pubs.truncate(3);
+                pubs
+            })
+            .unwrap_or_default();
+        let first_publish_year = doc
+            .get("first_publish_year")
+            .and_then(|y| y.as_i64())
+            .map(|y| y as i32);
+        let cover_i = doc.get("cover_i").and_then(|c| c.as_i64());
+        let cover_url = cover_i.map(|id| format!("https://covers.openlibrary.org/b/id/{}-M.jpg", id));
+        let key = doc
+            .get("key")
+            .and_then(|k| k.as_str())
+            .unwrap_or("")
+            .to_string();
+
+        let series_name = extract_series_name(&title);
+
+        let entry = series_map
+            .entry(series_name.clone())
+            .or_insert_with(|| SeriesCandidateBuilder {
+                title: series_name.clone(),
+                authors: vec![],
+                description: None,
+                publishers: vec![],
+                start_year: None,
+                volume_count: 0,
+                cover_url: None,
+                external_id: key.clone(),
+                external_url: if key.is_empty() {
+                    None
+                } else {
+                    Some(format!("https://openlibrary.org{}", key))
+                },
+            });
+
+        entry.volume_count += 1;
+
+        for a in &authors {
+            if !entry.authors.contains(a) {
+                entry.authors.push(a.clone());
+            }
+        }
+        for p in &publishers {
+            if !entry.publishers.contains(p) {
+                entry.publishers.push(p.clone());
+            }
+        }
+        if entry.start_year.is_none() || first_publish_year.map_or(false, |y| entry.start_year.unwrap() > y) {
+            if first_publish_year.is_some() {
+                entry.start_year = first_publish_year;
+            }
+        }
+        if entry.cover_url.is_none() {
+            entry.cover_url = cover_url;
+        }
+    }
+
+    let mut candidates: Vec<SeriesCandidate> = series_map
+        .into_values()
+        .map(|b| {
+            let confidence = compute_confidence(&b.title, &query_lower);
+            SeriesCandidate {
+                external_id: b.external_id,
+                title: b.title,
+                authors: b.authors,
+                description: b.description,
+                publishers: b.publishers,
+                start_year: b.start_year,
+                total_volumes: if b.volume_count > 1 { Some(b.volume_count) } else { None },
+                cover_url: b.cover_url,
+                external_url: b.external_url,
+                confidence,
+                metadata_json: serde_json::json!({}),
+            }
+        })
+        .collect();
+
+    candidates.sort_by(|a, b| b.confidence.partial_cmp(&a.confidence).unwrap_or(std::cmp::Ordering::Equal));
+    candidates.truncate(10);
+    Ok(candidates)
+}
+
+async fn get_series_books_impl(
+    external_id: &str,
+    _config: &ProviderConfig,
+) -> Result<Vec<BookCandidate>, String> {
+    let client = reqwest::Client::builder()
+        .timeout(std::time::Duration::from_secs(15))
+        .build()
+        .map_err(|e| format!("failed to build HTTP client: {e}"))?;
+
+    // Fetch the work to get its title for series search
+    let url = format!("https://openlibrary.org{}.json", external_id);
+    let resp = client.get(&url).send().await.map_err(|e| format!("Open Library request failed: {e}"))?;
+
+    let work: serde_json::Value = if resp.status().is_success() {
+        resp.json().await.map_err(|e| format!("Failed to parse response: {e}"))?
+    } else {
+        serde_json::json!({})
+    };
+
+    let title = work.get("title").and_then(|t| t.as_str()).unwrap_or("");
+    let series_name = extract_series_name(title);
+
+    // Search for editions of this series
+    let search_url = format!(
+        "https://openlibrary.org/search.json?title={}&limit=40",
+        urlencoded(&series_name)
+    );
+    let resp = client.get(&search_url).send().await.map_err(|e| format!("Open Library search failed: {e}"))?;
+
+    if !resp.status().is_success() {
+        return Ok(vec![]);
+    }
+
+    let data: serde_json::Value = resp.json().await.map_err(|e| format!("Failed to parse response: {e}"))?;
+    let docs = match data.get("docs").and_then(|d| d.as_array()) {
+        Some(docs) => docs,
+        None => return Ok(vec![]),
+    };
+
+    let mut books: Vec<BookCandidate> = docs
+        .iter()
+        .map(|doc| {
+            let title = doc.get("title").and_then(|t| t.as_str()).unwrap_or("").to_string();
+            let authors: Vec<String> = doc
+                .get("author_name")
+                .and_then(|a| a.as_array())
+                .map(|arr| arr.iter().filter_map(|v| v.as_str().map(String::from)).collect())
+                .unwrap_or_default();
+            let isbn = doc
+                .get("isbn")
+                .and_then(|a| a.as_array())
+                .and_then(|arr| arr.first())
+                .and_then(|v| v.as_str())
+                .map(String::from);
+            let page_count = doc
+                .get("number_of_pages_median")
+                .and_then(|n| n.as_i64())
+                .map(|n| n as i32);
+            let cover_i = doc.get("cover_i").and_then(|c| c.as_i64());
+            let cover_url = cover_i.map(|id| format!("https://covers.openlibrary.org/b/id/{}-M.jpg", id));
+            let language = doc
+                .get("language")
+                .and_then(|a| a.as_array())
+                .and_then(|arr| arr.first())
+                .and_then(|v| v.as_str())
+                .map(String::from);
+            let publish_date = doc
+                .get("first_publish_year")
+                .and_then(|y| y.as_i64())
+                .map(|y| y.to_string());
+            let key = doc.get("key").and_then(|k| k.as_str()).unwrap_or("").to_string();
+            let volume_number = extract_volume_number(&title);
+
+            BookCandidate {
+                external_book_id: key,
+                title,
+                volume_number,
+                authors,
+                isbn,
+                summary: None,
+                cover_url,
+                page_count,
+                language,
+                publish_date,
+                metadata_json: serde_json::json!({}),
+            }
+        })
+        .collect();
+
+    books.sort_by_key(|b| b.volume_number.unwrap_or(999));
+    Ok(books)
+}
+
+fn extract_series_name(title: &str) -> String {
+    let re_patterns = [
+        r"(?i)\s*[-–—]\s*(?:vol(?:ume)?\.?\s*|tome\s*|t\.\s*|#)\s*\d+.*$",
+        r"(?i)\s*,?\s*(?:vol(?:ume)?\.?\s*|tome\s*|t\.\s*|#)\s*\d+.*$",
+        r"\s*\(\d+\)\s*$",
+        r"\s+\d+\s*$",
+    ];
+    let mut result = title.to_string();
+    for pattern in &re_patterns {
+        if let Ok(re) = regex::Regex::new(pattern) {
+            let cleaned = re.replace(&result, "").to_string();
+            if !cleaned.is_empty() {
+                result = cleaned;
+                break;
+            }
+        }
+    }
+    result.trim().to_string()
+}
+
+fn extract_volume_number(title: &str) -> Option<i32> {
+    let patterns = [
+        r"(?i)(?:vol(?:ume)?\.?\s*|tome\s*|t\.\s*|#)\s*(\d+)",
+        r"\((\d+)\)\s*$",
+        r"\b(\d+)\s*$",
+    ];
+    for pattern in &patterns {
+        if let Ok(re) = regex::Regex::new(pattern) {
+            if let Some(caps) = re.captures(title) {
+                if let Some(num) = caps.get(1).and_then(|m| m.as_str().parse::<i32>().ok()) {
+                    return Some(num);
+                }
+            }
+        }
+    }
+    None
+}
+
+fn compute_confidence(title: &str, query: &str) -> f32 {
+    let title_lower = title.to_lowercase();
+    if title_lower == query {
+        1.0
+    } else if title_lower.starts_with(query) || query.starts_with(&title_lower) {
+        0.8
+    } else if title_lower.contains(query) || query.contains(&title_lower) {
+        0.7
+    } else {
+        let common: usize = query.chars().filter(|c| title_lower.contains(*c)).count();
+        let max_len = query.len().max(title_lower.len()).max(1);
+        (common as f32 / max_len as f32).clamp(0.1, 0.6)
+    }
+}
+
+fn urlencoded(s: &str) -> String {
+    let mut result = String::new();
+    for byte in s.bytes() {
+        match byte {
+            b'A'..=b'Z' | b'a'..=b'z' | b'0'..=b'9' | b'-' | b'_' | b'.' | b'~' => {
+                result.push(byte as char);
+            }
+            _ => result.push_str(&format!("%{:02X}", byte)),
+        }
+    }
+    result
+}
+
+struct SeriesCandidateBuilder {
+    title: String,
+    authors: Vec<String>,
+    description: Option<String>,
+    publishers: Vec<String>,
+    start_year: Option<i32>,
+    volume_count: i32,
+    cover_url: Option<String>,
+    external_id: String,
+    external_url: Option<String>,
+}