feat(ticket): 列表支持按标题/正文搜索

手机端工单列表要能像任务、知识一样搜。与知识列表同一套 ilike 匹配，标题记不清时正文关键词也能命中；补测试覆盖标题命中、正文命中、无结果三种情况。

backend/app/api/tickets.py

@@ -601,6 +601,7 @@ async def list_tickets(
     session: SessionDep,
     role: Annotated[str, Query(description="assigned|requested|all")] = "assigned",
     status: Annotated[list[str] | None, Query(description="按状态过滤，可重复")] = None,
+    q: Annotated[str | None, Query(description="搜标题或正文")] = None,
     limit: Annotated[int, Query(ge=1, le=100)] = 20,
     cursor: Annotated[str | None, Query()] = None,
 ) -> dict:
@@ -622,6 +623,11 @@ async def list_tickets(
     if status:
         stmt = stmt.where(Item.status.in_(status))
 
+    if q and q.strip():
+        # 与知识列表同一套模糊匹配：手机上找一张单，标题记不清时正文里的关键词也能命中
+        like = f"%{q.strip()}%"
+        stmt = stmt.where(or_(Item.title.ilike(like), Item.body_md.ilike(like)))
+
     stmt = stmt.order_by(Item.updated_at.desc(), Item.id.desc()).limit(limit + 1)
     if parsed_cursor is not None:
         stmt = stmt.where(