feat: v3 增强 - FTS5全文搜索+双向链接/知识图谱+自动保存草稿+标签管理+实时预览编辑器+PWA

- FTS5中文分词搜索(需-tags=sqlite_fts5)
- [[wiki链接]]反向链接+SVG知识图谱
- 自动保存草稿(不触发版本历史)
- 标签重命名/合并/删除+使用统计
- 后台编辑实时预览+格式工具栏
- PWA manifest+service worker+移动端适配
- 冒烟测试扩至66例全通过

web/manifest.json

@@ -0,0 +1,21 @@
+{
+  "name": "云笔记",
+  "short_name": "笔记",
+  "start_url": "/",
+  "scope": "/",
+  "display": "standalone",
+  "background_color": "#ffffff",
+  "theme_color": "#1a73e8",
+  "icons": [
+    {
+      "src": "/icon-192.png",
+      "sizes": "192x192",
+      "type": "image/png"
+    },
+    {
+      "src": "/icon-512.png",
+      "sizes": "512x512",
+      "type": "image/png"
+    }
+  ]
+}