feat: enhance Milkdown editor and file system functionality

- Normalize line endings in Markdown export for DOCX files.
- Improve selection serialization to Markdown with better handling of empty documents.
- Add a new `updateFile` function to the file system for updating file properties.
- Introduce video transcoding capabilities using FFmpeg, supporting various video formats.
- Update AGENTS.md for clearer plugin structure and responsibilities.
- Add scoped styles for TreeNodeItem component to improve UI consistency.
- Implement cross-origin isolation headers in Vite configuration for enhanced security.
- Remove obsolete test_cross.py file.

vite.config.js

@@ -1,11 +1,17 @@
 import { defineConfig } from 'vite'
 import vue from '@vitejs/plugin-vue'
 
+const crossOriginIsolationHeaders = {
+  'Cross-Origin-Embedder-Policy': 'require-corp',
+  'Cross-Origin-Opener-Policy': 'same-origin'
+}
+
 export default defineConfig({
   plugins: [vue()],
   server: {
     host: true,
     port: 5173,
+    headers: crossOriginIsolationHeaders,
     proxy: {
       '/v1': {
         target: 'https://api.imageteach.tech:8002',
@@ -13,6 +19,9 @@ export default defineConfig({
       }
     }
   },
+  preview: {
+    headers: crossOriginIsolationHeaders
+  },
   build: {
     rollupOptions: {
       output: {