test: Phase 3 添加 smoke test、CI 与 run-daily 去重锁

离线 mock 测试 generate 产出，GitHub Actions 跑 pytest，30 分钟内重复调度自动 skip。

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/fixtures/sample-rss.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<rss version="2.0">
+  <channel>
+    <title>Sample AI Feed</title>
+    <item>
+      <title>Sample AI headline for smoke tests</title>
+      <link>https://example.com/ai-news/1</link>
+      <pubDate>Wed, 02 Jul 2026 08:00:00 GMT</pubDate>
+      <description>A minimal RSS item used by offline tests.</description>
+    </item>
+  </channel>
+</rss>

tests/fixtures/skills-feed.json

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+{
+  "updatedAt": "2026-07-02T12:00:00Z",
+  "topTrending": [
+    {
+      "id": "vercel-labs/skills/find-skills",
+      "title": "find-skills",
+      "source": "vercel-labs/skills",
+      "installs": 18000,
+      "link": "https://www.skills.sh/vercel-labs/skills/find-skills",
+      "description": "Help users discover and install Agent Skills."
+    },
+    {
+      "id": "halt-catch-fire/skills/remotion-render",
+      "title": "remotion-render",
+      "source": "halt-catch-fire/skills",
+      "installs": 21549,
+      "link": "https://www.skills.sh/halt-catch-fire/skills/remotion-render",
+      "description": "Render videos from React/Remotion component code."
+    }
+  ],
+  "topHot": [
+    {
+      "id": "vercel-labs/skills/find-skills",
+      "title": "find-skills",
+      "source": "vercel-labs/skills",
+      "installs": 243,
+      "link": "https://www.skills.sh/vercel-labs/skills/find-skills",
+      "description": "Help users discover and install Agent Skills."
+    }
+  ],
+  "topAllTime": []
+}