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/message-jump.test.ts

@@ -0,0 +1,93 @@
+import { describe, expect, it } from 'vitest'
+import type { Message } from '../../src/shared/types'
+import { buildMessageGroups } from '../../src/renderer/src/components/chat/messageGrouping'
+import {
+  normalizeJumpMessageId,
+  resolveMessageJumpTarget
+} from '../../src/renderer/src/components/chat/messageJump'
+
+const message = (id: string, createTime: number, content = id): Message =>
+  ({
+    id,
+    from: 'user',
+    type: '普通文本',
+    datetime: '',
+    content,
+    isSender: false,
+    createTime
+  }) as Message
+
+/**
+ * 「跳转到原聊天」的定位契约。
+ *
+ * 必须**真的**落在那一条消息上，而不是"路由切过去了"。
+ * 秒级时间戳在群聊里对应多条消息，所以精确 id 必须优先。
+ */
+describe('resolveMessageJumpTarget', () => {
+  it('prefers the exact stable identity over the timestamp', () => {
+    const messages = [
+      message('m1', 1_700_000_000),
+      message('m2', 1_700_000_000),
+      message('m3', 1_700_000_000)
+    ]
+    const groups = buildMessageGroups(messages)
+
+    // 三条消息同一秒：只有 id 能定位到正确的那一条。
+    const target = resolveMessageJumpTarget(groups, 1_700_000_000, 'm3')
+    expect(target).toMatchObject({ messageId: 'm3', exact: true })
+  })
+
+  it('normalizes the synthetic local: prefix on both sides', () => {
+    // 归档侧存的是 `local:42`，证据侧的 messageRef 解出来是 `42` —— 必须视为同一条。
+    const groups = buildMessageGroups([message('local:42', 1_700_000_000)])
+    expect(normalizeJumpMessageId('local:42')).toBe('42')
+    expect(resolveMessageJumpTarget(groups, undefined, '42')).toMatchObject({
+      messageId: 'local:42',
+      exact: true
+    })
+    // 反过来也一样（证据侧带前缀、归档侧不带）。
+    const plain = buildMessageGroups([message('42', 1_700_000_000)])
+    expect(resolveMessageJumpTarget(plain, undefined, 'local:42')).toMatchObject({
+      messageId: '42',
+      exact: true
+    })
+  })
+
+  it('returns the archive-side id so the highlight comparison cannot silently mismatch', () => {
+    const groups = buildMessageGroups([message('local:17078', 1_700_000_000)])
+    const target = resolveMessageJumpTarget(groups, undefined, '17078')
+    // 传进去的是归一化后的 `17078`，但返回的必须是归档侧真实出现的 `local:17078`：
+    // MessageGroup 用 message.id 直接比对高亮。
+    expect(target?.messageId).toBe('local:17078')
+  })
+
+  it('falls back to the first message at or after the timestamp for legacy evidence', () => {
+    const groups = buildMessageGroups([
+      message('old', 1_690_000_000),
+      message('hit', 1_700_000_100),
+      message('newer', 1_700_000_200)
+    ])
+    expect(resolveMessageJumpTarget(groups, 1_700_000_000, undefined)).toMatchObject({
+      messageId: 'hit',
+      exact: false
+    })
+  })
+
+  it('reports nothing to jump to when the message no longer exists', () => {
+    const groups = buildMessageGroups([message('m1', 1_700_000_000)])
+    // 目标已被删除 / 清理，且时间戳晚于所有消息 → 调用方必须走诚实降级文案。
+    expect(resolveMessageJumpTarget(groups, 1_900_000_000, 'gone')).toBeNull()
+    expect(resolveMessageJumpTarget(groups, undefined, 'gone')).toBeNull()
+    expect(resolveMessageJumpTarget(groups, null, null)).toBeNull()
+  })
+
+  it('still resolves by id when the evidence carries no usable timestamp', () => {
+    const groups = buildMessageGroups([message('m1', 1_700_000_000), message('m2', 1_700_000_600)])
+    // 没有 createTime 的证据在真实数据里确实存在（老缓存），不能因此放弃定位。
+    expect(resolveMessageJumpTarget(groups, undefined, 'm1')).toMatchObject({
+      messageId: 'm1',
+      exact: true,
+      groupIndex: 0
+    })
+  })
+})