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

joke_sites.json

@@ -0,0 +1,98 @@
+[
+  {
+    "url": "https://www.52xiaohua.com/xiaohua/1105.html",
+    "title": "100个经典幽默笑话大全，笑到肚子疼超级爆笑 - 爆笑笑话 ...",
+    "keyword": "笑话大全 网站",
+    "domain": "www.52xiaohua.com",
+    "id": 1,
+    "found_at": "2026-05-31T10:17:46"
+  },
+  {
+    "url": "https://xiaohua.zol.com.cn/",
+    "title": "笑话大全-爆笑经典笑话 冷笑话【ZOL笑话库】",
+    "keyword": "笑话大全 网站",
+    "domain": "xiaohua.zol.com.cn",
+    "id": 2,
+    "found_at": "2026-05-31T10:17:46"
+  },
+  {
+    "url": "https://www.yjbys.com/xiaohua/baoxiao/439774.html",
+    "title": "经典笑话大全爆笑100条",
+    "keyword": "笑话大全 网站",
+    "domain": "www.yjbys.com",
+    "id": 3,
+    "found_at": "2026-05-31T10:17:46"
+  },
+  {
+    "url": "https://zhilezhi.com/xiaohua",
+    "title": "笑话大全 - 幽默笑话和搞笑段子网站 | 知乐知",
+    "keyword": "笑话大全 网站",
+    "domain": "zhilezhi.com",
+    "id": 4,
+    "found_at": "2026-05-31T10:17:46"
+  },
+  {
+    "url": "https://xiaohua.hao86.com/",
+    "title": "笑话大全爆笑简短_史上最强笑话十则2026",
+    "keyword": "笑话大全 网站",
+    "domain": "xiaohua.hao86.com",
+    "id": 5,
+    "found_at": "2026-05-31T10:17:46"
+  },
+  {
+    "url": "https://www.douyin.com/video/7457017269722402067",
+    "title": "搞笑视频合集。 每日一笑，烦恼忘掉。#搞笑 #搞笑视频 #看 ...",
+    "keyword": "搞笑段子 网站",
+    "domain": "www.douyin.com",
+    "id": 6,
+    "found_at": "2026-05-31T10:17:46"
+  },
+  {
+    "url": "https://www.iqiyi.com/v_fhial680gw.html",
+    "title": "搞笑沙雕短片合集恶搞整蛊让你乐不停-爱奇艺",
+    "keyword": "搞笑段子 网站",
+    "domain": "www.iqiyi.com",
+    "id": 7,
+    "found_at": "2026-05-31T10:17:46"
+  },
+  {
+    "url": "https://www.qiushidabaike.com/",
+    "title": "笑话大全_恶搞囧事 - 糗事大百科",
+    "keyword": "搞笑段子 网站",
+    "domain": "www.qiushidabaike.com",
+    "id": 8,
+    "found_at": "2026-05-31T10:17:46"
+  },
+  {
+    "url": "https://doc.quark.cn/preview/tongyongshenghuo-shejiaoyule-lengxiaohua%2Fxiaohua/C247E8B69B4BFB30FA3A859CC1A0C94B",
+    "title": "100个经典冷笑话大全爆笑",
+    "keyword": "冷笑话 大全",
+    "domain": "doc.quark.cn",
+    "id": 9,
+    "found_at": "2026-05-31T10:17:46"
+  },
+  {
+    "url": "https://www.meiwengushi.com/100gejingdianlengxiaohuadaquan",
+    "title": "100个经典冷笑话大全",
+    "keyword": "冷笑话 大全",
+    "domain": "www.meiwengushi.com",
+    "id": 10,
+    "found_at": "2026-05-31T10:17:46"
+  },
+  {
+    "url": "https://www.thepaper.cn/newsDetail_forward_17848009",
+    "title": "20个幽默冷笑话，个个爆笑不断，记得分享给身边朋友们",
+    "keyword": "幽默笑话 网站",
+    "domain": "www.thepaper.cn",
+    "id": 11,
+    "found_at": "2026-05-31T10:17:46"
+  },
+  {
+    "url": "https://baike.sogou.com/v65352.htm",
+    "title": "幽默 _ 百科",
+    "keyword": "幽默笑话 网站",
+    "domain": "baike.sogou.com",
+    "id": 12,
+    "found_at": "2026-05-31T10:17:46"
+  }
+]