feat: 重构问问微信并完善知识库增量检索

统一问问微信与 Agent Hub 的查询链路
完善查询覆盖度、新鲜度和部分结果表达，避免索引滞后产生错误结论
基于会话实现真正的增量追新与历史补齐
支持后台同步、取消恢复、重启续传以及同步期间继续查询
优化知识库跨会话检索、同步状态、进度展示和侧栏布局

tests/unit/query-agent-poc-report.test.ts

@@ -1,8 +1,8 @@
 import { describe, expect, it } from 'vitest'
 import { formatProviderDiagnostics, formatTiming } from '../../src/main/query-agent-poc-report'
-import type { QueryAgentPocResult } from '../../src/main/services/query-agent-poc-service'
+import type { QueryAgentResult } from '../../src/main/services/query-agent-service'
 
-function result(patch: Partial<QueryAgentPocResult> = {}): QueryAgentPocResult {
+function result(patch: Partial<QueryAgentResult> = {}): QueryAgentResult {
   return {
     question: 'q',
     provider: 'Fixture Provider',