feat: add series support for book organization

API:
- Add /libraries/{id}/series endpoint to list series with book counts
- Add series filter to /books endpoint
- Fix SeriesItem to return first_book_id properly (using CTE with ROW_NUMBER)

Indexer:
- Parse series from parent folder name relative to library root
- Store series in database when indexing books

Backoffice:
- Add Books page with grid view, search, and pagination
- Add Series page showing series with cover images
- Add Library books page filtered by series
- Add book detail page
- Add Series column in libraries list with clickable link
- Create BookCard component for reusable book display
- Add CSS styles for books grid, series grid, and book details
- Add proxy API route for book cover images (fixing CORS issues)

Parser:
- Add series field to ParsedMetadata
- Extract series from file path relative to library root

Books without a parent folder are categorized as 'unclassified' series.

apps/indexer/src/main.rs

@@ -228,14 +228,15 @@ async fn scan_library(
                 continue;
             }
 
-            match parse_metadata(path, format) {
+            match parse_metadata(path, format, root) {
                 Ok(parsed) => {
                     sqlx::query(
-                        "UPDATE books SET title = $2, kind = $3, page_count = $4, updated_at = NOW() WHERE id = $1",
+                        "UPDATE books SET title = $2, kind = $3, series = $4, page_count = $5, updated_at = NOW() WHERE id = $1",
                     )
                     .bind(book_id)
                     .bind(parsed.title)
                     .bind(kind_from_format(format))
+                    .bind(parsed.series)
                     .bind(parsed.page_count)
                     .execute(&state.pool)
                     .await?;
@@ -268,17 +269,18 @@ async fn scan_library(
             continue;
         }
 
-        match parse_metadata(path, format) {
+        match parse_metadata(path, format, root) {
             Ok(parsed) => {
                 let book_id = Uuid::new_v4();
                 let file_id = Uuid::new_v4();
                 sqlx::query(
-                    "INSERT INTO books (id, library_id, kind, title, page_count) VALUES ($1, $2, $3, $4, $5)",
+                    "INSERT INTO books (id, library_id, kind, title, series, page_count) VALUES ($1, $2, $3, $4, $5, $6)",
                 )
                 .bind(book_id)
                 .bind(library_id)
                 .bind(kind_from_format(format))
                 .bind(parsed.title)
+                .bind(parsed.series)
                 .bind(parsed.page_count)
                 .execute(&state.pool)
                 .await?;