feat(intelligence): implement Global AI Q&A screen and paywall blocker

- Implemented standard empty and active chat conversation states for the `/intelligence` page
- Created interactive `AiResponseRenderer` with AOT-compliant sentence splitting and payment gateway simulation
- Added scoped `LibraryStateService` to synchronize book ownership and updates across the application
- Obfuscated paywalled content in DOM to prevent inspection bypass
- Fixed local port connection mismatch by updating API configurations to use port 5104

src/NexusReader.Web/appsettings.Test.json

@@ -9,5 +9,5 @@
     "AllowRegistration": false,
     "AllowPasswordReset": false
   },
-  "ApiBaseUrl": "http://localhost:5000"
+  "ApiBaseUrl": "http://localhost:5104"
 }