feat(editor): CodeMirror 6 富编辑（图片内联/撤销/标题/草稿恢复/降级护栏）

Author: Aparencia

app/package-lock.json

@@ -11,10 +11,12 @@
     "tauri": "tauri"
   },
   "dependencies": {
+    "@codemirror/lang-markdown": "^6.5.2",
     "@tauri-apps/api": "^2",
     "@tauri-apps/plugin-dialog": "^2.7.2",
     "@types/katex": "^0.16.8",
     "@xyflow/react": "^12.11.3",
+    "codemirror": "^6.0.2",
     "katex": "^0.18.4",
     "react": "^19.1.0",
     "react-dom": "^19.1.0",