feat: full-text search (messages + customers)

Backend (yunke-server):
- GET /api/search?q=&type=messages|customers|all&channel=&start=&end=&page=&page_size=
  LIKE '%q%' scan over message.text + customer friend_nickname/real_name/
  phone/wechat_phone. type=all returns both sections; each is its own Page[T].
- type=messages orders by timestamp desc; type=customers orders by
  last_chat_time desc (nulls last).
- q required: missing/empty/whitespace -> HTTP 400.
- 14 new tests in tests/test_api_search.py (TDD red -> green).

Frontend (yunkes):
- New /search route + 搜索 nav item with Search icon.
- SearchView.vue: search bar, two stacked sections (消息结果 / 客户结果),
  counts + independent pagination per section, keyword highlighting (escaped),
  click message -> /chat/:channel/:ownerId/:talkerId,
  click customer -> all-fields drawer (CustomerList pattern reuse).
- search() wrapper in src/api/index.ts with SearchQuery/SearchPayload types.
- Empty state: "输入关键词搜索消息和客户".

Co-Authored-By: Claude <noreply@anthropic.com>

yunkes/src/api/index.ts

@@ -215,6 +215,49 @@ export function getSyncStatus(): Promise<SyncStatus> {
   return getJson<SyncStatus>('/sync/status')
 }
 
+// ---------------------------------------------------------------------------
+// Full-text search (messages + customers)
+// ---------------------------------------------------------------------------
+
+export type SearchType = 'messages' | 'customers' | 'all'
+
+export interface SearchQuery {
+  q: string
+  /** which section(s) to query; defaults to `all`. */
+  type?: SearchType
+  channel?: Channel | 'all'
+  /** ms-epoch inclusive window compared against message.timestamp. */
+  start?: number
+  end?: number
+  page?: number
+  page_size?: number
+}
+
+/**
+ * Combined search payload returned by `/api/search`. Each requested section is
+ * present; unrequested sections are omitted entirely by the backend (so the
+ * caller can branch on `section in payload`).
+ */
+export interface SearchPayload {
+  messages?: Page<Message>
+  customers?: Page<Customer>
+}
+
+export function search(query: SearchQuery): Promise<SearchPayload> {
+  return getJson<SearchPayload>(
+    '/search',
+    clean({
+      q: query.q,
+      type: query.type ?? 'all',
+      channel: query.channel === 'all' ? undefined : query.channel,
+      start: query.start,
+      end: query.end,
+      page: query.page ?? 1,
+      page_size: query.page_size ?? 20,
+    }),
+  )
+}
+
 export type {
   Account,
   CallChannel,