FIX: Enable scrollbars in CodeMirror editors and complete missing i18n

CodeMirror Scrollbar Fixes:
- Add EditorView.theme configurations with overflow: auto for .cm-scroller
- Configure scrollPastEnd: false in basicSetup for all CodeMirror instances
- Fix FileViewer, CredentialEditor, HostManagerEditor, and FileManagerFileEditor
- Ensure proper height: 100% styling for editor containers

i18n Completion:
- Add missing "movedItems" translation key for file move operations
- English: "Moved {{count}} items"
- Chinese: "已移动 {{count}} 个项目"

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

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

src/locales/zh/translation.json

@@ -760,6 +760,7 @@
     "deleteFiles": "删除 {{count}} 个项目",
     "filesCopiedToClipboard": "{{count}} 个项目已复制到剪贴板",
     "filesCutToClipboard": "{{count}} 个项目已剪切到剪贴板",
+    "movedItems": "已移动 {{count}} 个项目",
     "failedToDeleteItem": "删除项目失败",
     "itemRenamedSuccessfully": "{{type}}重命名成功",
     "failedToRenameItem": "重命名项目失败",