Implement file hash-based library matching and remove fuzzy ASIN matching

Adds file hash-based matching for Audiobookshelf library items to ensure 100% accurate ASIN assignment for RMAB-organized content. Removes fuzzy matching from library availability checks, making all matching ASIN-only to eliminate false positives and race conditions. Updates database schema, processors, and matcher utilities; adds new tests and documentation for the new matching strategy. Removes obsolete scripts, Dockerfile, and related tests; updates docker-compose for test environments.

documentation/integrations/audible.md

@@ -88,22 +88,29 @@ Where `{baseUrl}` is determined by configured region (e.g., `https://www.audible
 
 ## Unified Matching (`audiobook-matcher.ts`)
 
-**Status:** ✅ Production Ready
+**Status:** ✅ Production Ready (ASIN-Only Matching)
 
 Single matching algorithm used everywhere (search, popular, new-releases, jobs).
 
-**Process:**
-1. Query DB candidates: `audibleId` exact match OR partial title+author match
-2. If exact ASIN match → return immediately
-3. Fuzzy match: title 70% + author 30% weights, 70% threshold
-4. Return best match or null
+**Process (Library Availability Checks):**
+1. Query DB directly by ASIN (indexed O(1) lookup)
+2. Check ASIN in dedicated field (100% confidence)
+3. Check ASIN in plexGuid (backward compatibility)
+4. Return match or null (no fuzzy fallback)
+
+**Match Priority:**
+- `findPlexMatch()`: ASIN (field) → ASIN (GUID) → null
+- `matchAudiobook()`: ASIN → ISBN → null
 
 **Benefits:**
 - Real-time matching at query time (not pre-matched)
-- Works regardless of job execution order
-- Prevents duplicate `plexGuid` assignments
+- 100% confidence matches only (eliminates false positives)
+- O(1) indexed lookups (faster than fuzzy matching)
+- Solves race condition with Audiobookshelf ASIN population
 - Used by all APIs for consistency
 
+**Note:** Fuzzy matching (70% threshold) is preserved in `ranking-algorithm.ts` for Prowlarr torrent ranking, where it's needed to score multiple release candidates. Library availability checks require exact ASIN matches only.
+
 ## Database-First Approach
 
 **Status:** ✅ Implemented

documentation/integrations/ebook-sidecar.md

@@ -77,7 +77,7 @@ Anna's Archive uses Cloudflare protection which may block direct scraping reques
 
 **Method 1: ASIN Search (exact match)**
 ```
-Search: https://annas-archive.li/search?ext=epub&q="asin:B09TWSRMCB"
+Search: https://annas-archive.li/search?ext=epub&lang=en&q="asin:B09TWSRMCB"
   ↓
 MD5 Page: https://annas-archive.li/md5/[md5]
   ↓ (Filter: "slow partner server" links)

documentation/integrations/plex.md

@@ -21,6 +21,7 @@ Connectivity to Plex for OAuth, library management, content detection, and autom
 **GET {server_url}/library/sections/{id}/refresh** - Trigger async scan
 **GET {server_url}/library/metadata/{rating_key}** - Item metadata (includes user's personal rating)
 **GET {server_url}/library/sections/{id}/search?title={query}** - Search
+**DELETE {server_url}/library/metadata/{rating_key}** - Delete library item (requires deletion enabled in Plex settings)
 
 Auth: `X-Plex-Token` header
 Response: XML (requires `xml2js` parsing to JSON)
@@ -256,14 +257,41 @@ interface PlexLibrary {
   - testConnection() only used for: testing connections, initial fetching during setup/settings
 - Result: Faster authentication, no unnecessary API calls, consistent architecture
 
+## Library Item Deletion
+
+**Endpoint:** `DELETE /library/metadata/{ratingKey}`
+
+**Use Case:** When admin deletes a request, also delete from Plex library to keep in sync
+
+**Requirements:**
+- Deletion must be enabled: Settings > Server > Library in Plex webui
+- Without this setting enabled, DELETE requests will fail
+
+**Implementation:**
+- `deleteItem(serverUrl, authToken, ratingKey)` - Deletes library item by ratingKey
+- Called during request deletion when backend mode is 'plex'
+- Extracts ratingKey from audiobook.plexGuid (format: `plex://album/{ratingKey}`)
+- Mirrors ABS deletion behavior for consistency
+
+**Error Handling:**
+- 404: Item not found (already deleted) - logged but not thrown
+- Other errors: Logged but deletion continues (prevents blocking request deletion)
+
 ## Availability Checking
 
-1. **DB Population:** Plex scan creates/updates records with `plexGuid` + `availabilityStatus: 'available'`
-2. **Audible Matching:** Refresh job fuzzy matches (85% threshold), sets `availabilityStatus: 'available'` for matches
-3. **API Enrichment:** Discovery APIs use real-time matching (70% threshold) at query time
-4. **UI:** `AudiobookCard` shows "In Your Library" if `isAvailable: true`
+1. **DB Population:** Plex scan creates/updates records with `plexGuid` + ASIN + `availabilityStatus: 'available'`
+2. **Audible Matching:** Real-time ASIN-only matching (100% confidence, exact matches only)
+3. **API Enrichment:** Discovery APIs use real-time ASIN matching at query time
+4. **UI:** `AudiobookCard` shows "In Your Library" if `isAvailable: true` (ASIN exact match)
 5. **Server Validation:** `/api/requests` returns 409 if `availabilityStatus === 'available'`
 
+**Match Priority (ASIN-Only):**
+- ASIN in dedicated field (100% confidence) → Match
+- ASIN in plexGuid (backward compatibility) → Match
+- No ASIN match → Return null (no fuzzy fallback)
+
+**Note:** Fuzzy matching (70% threshold) is preserved in `ranking-algorithm.ts` for Prowlarr torrent selection, but NOT used for library availability checks. This eliminates false positives (e.g., "Foundation" matching "Foundation and Empire").
+
 ## Tech Stack
 
 - axios/node-fetch