feat: 优化问问微信检索性能与分析交互

- 补充 Worker、WCDB、sender、IPC、序列化时间账
- 增加 Agent 增量覆盖统计和重复检索停止条件
- 补充性能与交互回归测试

tests/integration/preload-contract.test.ts

@@ -56,6 +56,8 @@ describe('preload IPC contract', () => {
     }
     await api.runAiSearch(aiSearch)
     expect(invoke).toHaveBeenLastCalledWith('ai-search:run', aiSearch)
+    await api.cancelAiSearch(aiSearch.requestId)
+    expect(invoke).toHaveBeenLastCalledWith('ai-search:cancel', aiSearch.requestId)
     await api.startKnowledgeIndex()
     expect(invoke).toHaveBeenLastCalledWith('knowledge:startIndex')
     await api.clearCache('knowledge')