v5.1: 全面代码审查修复 — 安全加固 + 功能修复 + 测试补全 + 工程化

安全修复 (CRITICAL):
- 启用 CSP (default-src 'self')
- read_text_file 限制文件扩展名白名单 (.json/.csv/.txt)
- capabilities 显式声明窗口权限
- profile 名校验增强 (null 字节/控制字符/长度限制)

功能修复 (HIGH):
- AnalyzeDialog 重新打开时正确刷新数据
- UndoRedoButtons 订阅路径长度变化确保响应性
- 禁用状态持久化错误处理 (.catch → console.warn)
- 硬编码中文全部迁移到 i18n (6 处)
- PATH 长度检查改用 UTF-16 字符计数
- PATH 写入前 null 字节校验
- CLI export 拒绝写入系统目录
- savePaths 职责分离: window.confirm → Tauri ask() 对话框

代码质量 (MEDIUM):
- 导入路径统一过滤 (sanitize_paths: null 字节/分号/空白)
- 原子写入 (atomic_write: disabled.json + profiles)
- 验证缓存自动清理 (PathTable useEffect)
- Scanner 线程错误处理改进 (.unwrap → .map_err)
- Ctrl+F 去重 (移除 use-keyboard 重复处理)
- Profile 路径列表 key 修复 (index → path)
- 生产构建启用日志插件 (Warn 级别)
- export_paths JSON 序列化改 expect

测试:
- Rust: 35 → 48 测试 (+13)
- Frontend: 80 → 85 测试 (+5)
- Vitest 全局 jsdom + 覆盖率阈值 (80%)
- 安装 @vitest/coverage-v8 + test:coverage 脚本
- 移除未使用的 @testing-library/jest-dom

工程化:
- CI 添加 Cargo 缓存 (Swatinem/rust-cache@v2)
- CI 添加 cargo fmt --check
- tsconfig.test.json 覆盖测试文件类型检查
- cargo fmt 全量格式化

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/i18n/locales/en.json

@@ -8,6 +8,9 @@
     "user": "User Variables",
     "merged": "Merge Preview"
   },
+  "table": {
+    "path": "Path"
+  },
   "button": {
     "new": "New",
     "edit": "Edit",
@@ -51,7 +54,8 @@
     "readonly_label": "Read-only",
     "light": "Light",
     "dark": "Dark",
-    "adminWarning": "Running without administrator privileges, some features are disabled"
+    "adminWarning": "Running without administrator privileges, some features are disabled",
+    "saveWarningLongPaths": "PATH length exceeds recommended value. Continue saving?"
   },
   "dialog": {
     "newPath": "New Path",
@@ -70,7 +74,9 @@
     "backupMessage": "Back up registry before saving?",
     "confirm": "Confirm",
     "cancel": "Cancel",
-    "search": "Search paths..."
+    "search": "Search paths...",
+    "importSystemCount": "System: {{count}} entries",
+    "importUserCount": "User: {{count}} entries"
   },
   "analyze": {
     "title": "PATH Analysis",
@@ -82,7 +88,8 @@
     "priority": "Prioritized",
     "shadowed": "Shadowed",
     "searchPlaceholder": "Search executable name...",
-    "conflictCount": "{{count}} file conflict(s) found"
+    "conflictCount": "{{count}} file conflict(s) found",
+    "notExists": "(not found)"
   },
   "profile": {
     "title": "PATH Profiles",
@@ -95,7 +102,9 @@
     "rename": "Rename",
     "noProfiles": "No saved profiles",
     "applyConfirm": "This will overwrite current PATH with profile \"{{name}}\" and write to registry. Confirm?",
-    "deleted": "Profile \"{{name}}\" deleted"
+    "deleted": "Profile \"{{name}}\" deleted",
+    "selectProfile": "Select a profile",
+    "empty": "(empty)"
   },
   "help": {
     "content": "PathEditor v5.0 — Windows System Environment Variable (PATH) Editor\n\nFeatures:\n• Create/Edit/Delete path entries\n• Move Up/Down to adjust priority\n• One-click cleanup of invalid & duplicate paths\n• Import/Export JSON, CSV, TXT formats\n• Full Undo/Redo support\n\nShortcuts:\n• Ctrl+N New\n• Ctrl+S Save\n• Ctrl+Z Undo\n• Ctrl+Y Redo\n• Ctrl+F Search\n• Delete Delete selected\n• F1 Help\n\nAuthor: 刘航宇\nGitHub: https://github.com/LHY0125/PathEditor"