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/setup/complete/route.ts

@@ -412,6 +412,18 @@ export async function POST(request: NextRequest) {
       },
     });
 
+    // Chapter merging configuration
+    await prisma.configuration.upsert({
+      where: { key: 'chapter_merging_enabled' },
+      update: { value: String(paths.chapter_merging_enabled ?? false) },
+      create: {
+        key: 'chapter_merging_enabled',
+        value: String(paths.chapter_merging_enabled ?? false),
+        category: 'automation',
+        description: 'Automatically merge multi-file chapter downloads into single M4B with chapter markers'
+      },
+    });
+
     // BookDate configuration (optional, global for all users)
     // Note: libraryScope and customPrompt are now per-user settings, not required here
     if (bookdate && bookdate.provider && bookdate.apiKey && bookdate.model) {