feat: 添加知识库检索功能和改进模型路由错误处理

- 在ChatRequest中添加Citation事件类型，支持引用来源展示
- 实现聊天上下文准备服务，构建带源元数据的受限聊天上下文
- 添加ThreadedProcess类以支持Windows平台的子进程操作
- 改进检索引擎中的错误处理和向量搜索逻辑
- 实现严格的嵌入模型验证和索引重建机制
- 添加前端聊天界面的知识库检索开关
- 实现搜索历史记录功能和错误降级处理
- 更新模型路由设置提示信息以反映索引重建需求

frontend/src/stores/search.spec.ts

@@ -0,0 +1,40 @@
+// @vitest-environment happy-dom
+import { beforeEach, expect, it, vi } from 'vitest'
+import { createPinia, setActivePinia } from 'pinia'
+import { useSearchStore } from './search'
+import { search } from '@/services/searchService'
+
+vi.mock('@/services/searchService', () => ({ search: vi.fn() }))
+beforeEach(() => {
+  localStorage.clear()
+  setActivePinia(createPinia())
+  vi.mocked(search).mockReset().mockResolvedValue({ results: [], total: 0, mode: 'hybrid' })
+})
+
+it('persists real queries across store recreation, reorders duplicates and clears history', async () => {
+  const store = useSearchStore()
+  expect(store.recentQueries).toEqual([])
+  await store.doSearch({ query: ' first ' })
+  await store.doSearch({ query: 'second' })
+  await store.doSearch({ query: 'first' })
+  setActivePinia(createPinia())
+  const restored = useSearchStore()
+  expect(restored.recentQueries).toEqual(['first', 'second'])
+  restored.clearHistory()
+  setActivePinia(createPinia())
+  expect(useSearchStore().recentQueries).toEqual([])
+})
+
+it('ignores corrupt storage and does not let a stale request overwrite the latest search', async () => {
+  localStorage.setItem('notes-agent.search-history.v1', '{bad')
+  let finish!: (value: Awaited<ReturnType<typeof search>>) => void
+  vi.mocked(search).mockImplementationOnce(() => new Promise(resolve => { finish = resolve }))
+  const store = useSearchStore()
+  const first = store.doSearch({ query: 'old' })
+  await store.doSearch({ query: 'new' })
+  finish({ results: [], total: 99, mode: 'hybrid' })
+  await first
+  expect(store.total).toBe(0)
+  expect(store.query).toBe('new')
+  expect(store.recentQueries).toEqual(['new', 'old'])
+})