新增: AI 工具意图识别层 + 文件访问权限模型 Phase B+C

会话意图识别层(intent.rs / df-ai crate):
- Intent 枚举 11 态 + recognize 规则识别(关键词+权重+优先级)+ tool_subset_for 工具子集映射
- 模态接口预留 None,独立模块待接入 loop,36 单测

文件访问权限模型 Phase B+C(F-260619-03):
- Phase B 会话临时白名单 + 循环挂起 + DirAuthDialog 弹窗(仅本次/未来都允许/拒绝)
- Phase C 系统目录黑名单(Win System32/Program Files;Unix /etc /usr...)分段匹配 + 写操作约束
- 已审 CR-260619-09 ✅ PASS

src/i18n/en/aiChat.ts

@@ -145,6 +145,14 @@ export default {
     continueLoopFailed: 'Continue failed: {msg}',
     stopLoopFailed: 'Stop failed: {msg}',
 
+    // ── F-260619-03 Phase B: path authorization dialog (LLM accessing dir outside whitelist) ──
+    dirAuthRequired: 'Path authorization required',
+    dirAuthHint: '{tool} wants to access: {path}',
+    dirAuthOnce: 'This time',
+    dirAuthAlways: 'Always allow',
+    dirAuthDeny: 'Deny',
+    dirAuthFailed: 'Authorization failed: {msg}',
+
     // ── UX-18: conversation export (sidebar hover, pick format to download) ──
     exportConversation: 'Export chat',
     exportMarkdown: 'Markdown',