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/joke.py

@@ -12,6 +12,9 @@ class Joke(Base):
     id = Column(Integer, primary_key=True, autoincrement=True)
     title = Column(String(200), nullable=False)
     content = Column(Text, nullable=False)
+    polished_content = Column(Text, nullable=True)
+    type_ids = Column(Text, nullable=True)
+    crowd_ids = Column(Text, nullable=True)
     type_id = Column(Integer, ForeignKey("joke_types.id"), nullable=True)
     crowd_id = Column(Integer, ForeignKey("joke_crowds.id"), nullable=True)
     status = Column(String(20), default="pending")