Implement chapter merging feature and update ranking algorithm

Added automatic chapter merging to M4B with admin/config toggles, UI controls, and backend logic. Updated documentation to reflect implementation. Refactored ranking algorithm: increased Title/Author match points, removed size scoring, and improved Usenet/torrent handling. Enhanced Prowlarr integration for protocol detection and filtering. Improved file organizer to support chapter merging. Various bug fixes and logging improvements.

documentation/TABLEOFCONTENTS.md

@@ -48,7 +48,7 @@
 - **qBittorrent integration (torrents)** → [phase3/qbittorrent.md](phase3/qbittorrent.md)
 - **SABnzbd integration (Usenet/NZB)** → [phase3/sabnzbd.md](phase3/sabnzbd.md)
 - **File organization, seeding** → [phase3/file-organization.md](phase3/file-organization.md)
-- **Chapter merging (PRD, not implemented)** → [features/chapter-merging.md](features/chapter-merging.md)
+- **Chapter merging (auto-merge to M4B)** → [features/chapter-merging.md](features/chapter-merging.md)
 
 ## Background Jobs
 - **Bull queue, processors, retry logic** → [backend/services/jobs.md](backend/services/jobs.md)
@@ -93,7 +93,7 @@
 **"How do I use the unified container?"** → [deployment/unified.md](deployment/unified.md)
 **"OAuth redirects to localhost / PUBLIC_URL not working"** → [backend/services/environment.md](backend/services/environment.md)
 **"What environment variables do I need?"** → [backend/services/environment.md](backend/services/environment.md)
-**"How does chapter merging work?"** → [features/chapter-merging.md](features/chapter-merging.md) (PRD only, not implemented)
+**"How does chapter merging work?"** → [features/chapter-merging.md](features/chapter-merging.md)
 **"How does Audiobookshelf integration work?"** → [features/audiobookshelf-integration.md](features/audiobookshelf-integration.md) (PRD only, not implemented)
 **"How do I use OIDC/Authentik/Keycloak?"** → [features/audiobookshelf-integration.md](features/audiobookshelf-integration.md) (PRD only, not implemented)
 **"How does manual user registration work?"** → [features/audiobookshelf-integration.md](features/audiobookshelf-integration.md) (PRD only, not implemented)

documentation/features/chapter-merging.md

@@ -1,6 +1,6 @@
 # Chapter Merging Feature
 
-**Status:** ❌ Not Started | Product Requirements Document
+**Status:** ✅ Implemented | Auto-merge multi-file chapters to M4B
 
 ## Overview
 

documentation/phase3/ranking-algorithm.md

@@ -6,7 +6,7 @@ Evaluates and scores torrents to automatically select best audiobook download.
 
 ## Scoring Criteria (100 points max)
 
-**1. Title/Author Match (50 pts max) - MOST IMPORTANT**
+**1. Title/Author Match (60 pts max) - MOST IMPORTANT**
 
 **Multi-Stage Matching:**
 
@@ -24,7 +24,7 @@ Evaluates and scores torrents to automatically select best audiobook download.
   - "Dennis E. Taylor - Bobiverse - 01 - We Are Legion" → 3/3 = 100% → **PASSES**
 - Prevents wrong series books from matching while handling common subtitle patterns
 
-**Stage 2: Title Matching (0-35 pts)**
+**Stage 2: Title Matching (0-45 pts)**
 - Only scored if Stage 1 passes
 - **Tries full title first, then required title (without parentheses)** if no match
   - Example: "We Are Legion (We Are Bob)" tries both full title and "We Are Legion"
@@ -35,7 +35,7 @@ Evaluates and scores torrents to automatically select best audiobook download.
     - Title preceded by metadata separator (` - `, `: `, `—`) — handles "Author - Series - 01 - Title"
     - Author name appears in prefix — handles "Author Name - Title"
   - **Acceptable suffix**: Followed by metadata markers: " by", " [", " -", " (", " {", " :", "," or end of string
-- Complete match → 35 pts
+- Complete match → 45 pts
 - Unstructured prefix (words without separators) → fuzzy similarity (partial credit)
   - Prevents: "This Inevitable Ruin Dungeon Crawler Carl" matching "Dungeon Crawler Carl"
 - Suffix continues with non-metadata → fuzzy similarity (partial credit)
@@ -61,12 +61,7 @@ Evaluates and scores torrents to automatically select best audiobook download.
 **3. Seeder Count (15 pts max)**
 - Formula: `Math.min(15, Math.log10(seeders + 1) * 6)`
 - 1 seeder: 0pts, 10 seeders: 6pts, 100 seeders: 12pts, 1000+: 15pts
-
-**4. Size Reasonableness (10 pts max)**
-- Expected: 1-2 MB/min (64-128 kbps)
-- Perfect match: 10 pts
-- Deviation → penalty
-- Unknown duration: 5 pts (neutral)
+- Note: Usenet/NZB results without seeders get full 15 pts (centralized availability)
 
 ## Bonus Points System
 
@@ -148,7 +143,6 @@ interface RankedTorrent extends TorrentResult {
   breakdown: {
     formatScore: number;
     seederScore: number;
-    sizeScore: number;
     matchScore: number;
     totalScore: number;      // Same as score
     notes: string[];