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

admin/src/api/link.js

@@ -0,0 +1,7 @@
+import request from './request'
+
+export const getLinks = () => request.get('/admin/links')
+export const getLink = id => request.get('/admin/links/' + id)
+export const createLink = data => request.post('/admin/links', data)
+export const updateLink = (id, data) => request.put('/admin/links/' + id, data)
+export const deleteLink = id => request.delete('/admin/links/' + id)