FIX: Complete CodeMirror integration with native search, replace, and keyboard shortcuts

- Replace custom search/replace implementation with native CodeMirror extensions
- Add proper keyboard shortcut support: Ctrl+F, Ctrl+H, Ctrl+/, Ctrl+Space, etc.
- Fix browser shortcut conflicts by preventing defaults only when editor is focused
- Integrate autocompletion and comment toggle functionality
- Fix file name truncation in file manager grid to use text wrapping
- Add comprehensive keyboard shortcuts help panel for users
- Update i18n translations for editor buttons (Download, Replace, Replace All)
- Unify text and code file editing under single CodeMirror instance
- Add proper SSH HMAC algorithms for better compatibility

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

package.json

@@ -26,6 +26,9 @@
     "migrate:encryption": "tsc -p tsconfig.node.json && node ./dist/backend/backend/utils/encryption-migration.js"
   },
   "dependencies": {
+    "@codemirror/autocomplete": "^6.18.7",
+    "@codemirror/comment": "^0.19.1",
+    "@codemirror/search": "^6.5.11",
     "@hookform/resolvers": "^5.1.1",
     "@monaco-editor/react": "^4.7.0",
     "@radix-ui/react-accordion": "^1.2.11",