fix: resolve 10 code review issues

High priority:
- Fix concurrent race condition for view_count/like_count (atomic update)
- Add route request ID tracking to prevent race conditions
- Filter get_joke by status=approved (no pending content leak)
- Add error feedback for like button

Performance:
- Optimize random joke query (avoid full table sort)
- Limit page_size max to 100 (DoS prevention)

Medium:
- Add localStorage quota error handling
- Handle empty AI response gracefully
- Fix generate content title extraction

Low:
- Add rejected_jokes to stats API
- Update dashboard to show rejected count

api/app/models/__init__.py

@@ -1,5 +1,8 @@
 from app.models.joke import Joke
 from app.models.category import JokeType, JokeCrowd
 from app.models.user import AdminUser
+from app.models.setting import AiSetting
+from app.models.link import Link
+from app.models.feedback import Feedback
 
-__all__ = ["Joke", "JokeType", "JokeCrowd", "AdminUser"]
+__all__ = ["Joke", "JokeType", "JokeCrowd", "AdminUser", "AiSetting", "Link", "Feedback"]