新增: namespace淘汰治理与可恢复会话分组

- namespace 淘汰治理: pin 机制(关键产出 LRU 永不淘汰, 超池 50% 最旧降级) + EvictionLog 留档富提示(原工具名+内容摘要+重调指引) + owner 软隔离(无主最旧先淘); 子代理报告出口 pin 收编
- 错误路径广播 AiAgentFinished(status=error): 错误任务有终态, watcher/任务卡可收敛
- 桌面侧栏可恢复分组: parked 会话独立分组+点击恢复, 断点续跑读侧闭环
- 验收: cargo check 零 error + vue-tsc EXIT 0

src/i18n/en/aiChat.ts

@@ -21,6 +21,10 @@ export default {
     moreActions: 'More actions',
     archived: 'Archived',
     archivedCount: 'Archived ({n})',
+    recoverableCount: 'Recoverable ({n})',
+    recoverableHint: 'Task parked by restart interruption; click to resume',
+    recoverableDone: 'Task resumed, running in background',
+    recoverableFail: 'Recover failed: {msg}',
     emptyConversation: 'No conversations',
     // UX-06 §3.1: conversation search (live title filter, Ctrl+K to focus)
     searchPlaceholder: 'Search chats…',