chore(gerp): 移除死依赖（FormKit/tinymce-i18n/@vxe-ui/plugin-render-element/vite-plugin-static-copy）并修正误导注释

- package.json: 移除 4 个未使用依赖，lock 同步（-27 包）
- main.ts: 去掉 FormKit 全局注册与对应 chunk
- vite.config.ts: 去掉 formkit manualChunk
- RichTextEditor.vue: 修正加载方式注释（自写 copyTinymceAssets 而非 vite-plugin-static-copy）

package.json

@@ -10,15 +10,12 @@
   },
   "dependencies": {
     "@element-plus/icons-vue": "^2.3.2",
-    "@formkit/vue": "^2.1.2",
     "@fortawesome/fontawesome-free": "^7.3.1",
     "@vxe-ui/core": "^4.4.19",
-    "@vxe-ui/plugin-render-element": "^4.4.1",
     "axios": "^1.19.0",
     "element-plus": "^2.14.3",
     "marked": "^18.0.9",
     "pinia": "^4.0.2",
-    "tinymce-i18n": "^26.8.2",
     "turndown": "^7.2.4",
     "vue": "^3.5.40",
     "vue-router": "^5.2.0",
@@ -36,7 +33,6 @@
     "unplugin-auto-import": "^21.0.0",
     "unplugin-vue-components": "^32.1.0",
     "vite": "^8.2.0",
-    "vite-plugin-static-copy": "^4.1.1",
     "vue-tsc": "^3.3.8"
   }
 }