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

web/src/components/Footer.vue

@@ -1,15 +1,54 @@
 <template>
-  <footer class="footer">
-    <p>笑话大全 - 让快乐传递</p>
+  <footer class="app-footer">
+    <div class="footer-inner">
+      <nav class="footer-nav">
+        <router-link to="/" class="footer-link">首页</router-link>
+        <router-link to="/links" class="footer-link">友情链接</router-link>
+        <router-link to="/feedback" class="footer-link">意见建议</router-link>
+        <router-link to="/contact" class="footer-link">联系我们</router-link>
+      </nav>
+      <p class="footer-copyright">笑话大全 &mdash; 让快乐传递每一刻</p>
+    </div>
   </footer>
 </template>
 
 <style scoped>
-.footer {
-  background: #333;
-  color: white;
+.app-footer {
+  background: var(--bg-card);
+  border-top: 1px solid var(--border);
+  padding: 24px 20px;
   text-align: center;
-  padding: 20px;
   margin-top: auto;
+  transition: background 0.3s, border-color 0.3s;
 }
-</style>
+
+.footer-inner {
+  max-width: 1440px;
+  margin: 0 auto;
+}
+
+.footer-nav {
+  display: flex;
+  justify-content: center;
+  gap: 24px;
+  margin-bottom: 14px;
+  flex-wrap: wrap;
+}
+
+.footer-link {
+  color: var(--text-secondary);
+  text-decoration: none;
+  font-size: 14px;
+  transition: color 0.2s;
+}
+
+.footer-link:hover {
+  color: var(--primary);
+}
+
+.footer-copyright {
+  color: var(--text-muted);
+  font-size: 13px;
+  margin: 0;
+}
+</style>