feat: two-phase indexation with direct thumbnail generation in indexer

Phase 1 (discovery): walkdir + filename-only metadata, zero archive I/O.
Books are visible immediately in the UI while Phase 2 runs in background.

Phase 2 (analysis): open each archive once via analyze_book() to extract
page_count and first page bytes, then generate WebP thumbnail directly in
the indexer — removing the HTTP roundtrip to the API checkup endpoint.

- Add parse_metadata_fast() (infallible, no archive I/O)
- Add analyze_book() returning (page_count, first_page_bytes) in one pass
- Add looks_like_image() magic bytes check for unrar p stdout validation
- Add lsar fallback in list_cbr_images() for UTF-16BE encoded filenames
- Add directory_mtimes table to skip unchanged dirs on incremental scans
- Add analyzer.rs: generate_thumbnail, analyze_library_books, regenerate_thumbnails
- Remove run_checkup() from API; indexer handles thumbnail jobs directly
- Remove api_base_url/api_bootstrap_token from IndexerConfig and AppState
- Add unar + poppler-utils to indexer Dockerfile
- Fix smoke.sh: wait for job completion, check thumbnail_url field

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

crates/core/src/config.rs

@@ -32,10 +32,6 @@ pub struct IndexerConfig {
     pub meili_master_key: String,
     pub scan_interval_seconds: u64,
     pub thumbnail_config: ThumbnailConfig,
-    /// API base URL for thumbnail checkup at end of build (e.g. http://api:7080)
-    pub api_base_url: String,
-    /// Token to call API (e.g. API_BOOTSTRAP_TOKEN)
-    pub api_bootstrap_token: String,
 }
 
 #[derive(Debug, Clone)]
@@ -97,10 +93,6 @@ impl IndexerConfig {
                 .and_then(|v| v.parse::<u64>().ok())
                 .unwrap_or(5),
             thumbnail_config,
-            api_base_url: std::env::var("API_BASE_URL")
-                .unwrap_or_else(|_| "http://api:7080".to_string()),
-            api_bootstrap_token: std::env::var("API_BOOTSTRAP_TOKEN")
-                .context("API_BOOTSTRAP_TOKEN is required for thumbnail checkup")?,
         })
     }
 }