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.

src/app/api/admin/settings/paths/route.ts

@@ -11,7 +11,7 @@ export async function PUT(request: NextRequest) {
   return requireAuth(request, async (req: AuthenticatedRequest) => {
     return requireAdmin(req, async () => {
       try {
-        const { downloadDir, mediaDir, metadataTaggingEnabled } = await request.json();
+        const { downloadDir, mediaDir, metadataTaggingEnabled, chapterMergingEnabled } = await request.json();
 
         if (!downloadDir || !mediaDir) {
           return NextResponse.json(
@@ -53,6 +53,18 @@ export async function PUT(request: NextRequest) {
           },
         });
 
+        // Update chapter merging setting
+        await prisma.configuration.upsert({
+          where: { key: 'chapter_merging_enabled' },
+          update: { value: String(chapterMergingEnabled ?? false) },
+          create: {
+            key: 'chapter_merging_enabled',
+            value: String(chapterMergingEnabled ?? false),
+            category: 'automation',
+            description: 'Automatically merge multi-file chapter downloads into single M4B with chapter markers',
+          },
+        });
+
         console.log('[Admin] Paths settings updated');
 
         // Invalidate qBittorrent service singleton to force reload of download_dir

src/app/api/admin/settings/route.ts

@@ -81,6 +81,7 @@ export async function GET(request: NextRequest) {
         downloadDir: configMap.get('download_dir') || '/downloads',
         mediaDir: configMap.get('media_dir') || '/media/audiobooks',
         metadataTaggingEnabled: configMap.get('metadata_tagging_enabled') === 'true',
+        chapterMergingEnabled: configMap.get('chapter_merging_enabled') === 'true',
       },
       ebook: {
         enabled: configMap.get('ebook_sidecar_enabled') === 'true',