fix(xss+perf): SearchView XSS消除(无v-html)+room_id索引+pool_recycle

- SearchView.vue: 用 highlightSegments() 返回 {text,hit} 数组替代 v-html+escapeHtml+regex,模板用 <template v-for> + <mark>/<span> 渲染,从结构上消除 XSS 风险(4 处 v-html 全部移除: 消息片段/客户昵称/realName/手机号)
- models.py: Message 新增 ix_message_channel_owner_room_time(channel,owner_account_id,room_id,timestamp),群聊查询过滤 room_id 而非 talker_id,原 talker 索引无法覆盖
- migrations/d8eee96cd017: 新增 room_id 索引的 upgrade/downgrade (offline SQL 已验证)
- base.py + scheduler.py + cli.py: 所有生产 create_async_engine 增加 pool_recycle=3600,在 MySQL wait_timeout(默认 8h)断连前主动回收

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

yunke-server/app/db/models.py

@@ -399,6 +399,17 @@ class Message(Base):
             "talker_id",
             "timestamp",
         ),
+        # Group-chat hot path: per-account, per-room, time-ordered pagination.
+        # Group messages filter on room_id (not talker_id, which is the *other
+        # party* in a DM); without this index MySQL scans the talker index then
+        # refilters on room_id, which on high-volume accounts degrades fast.
+        Index(
+            "ix_message_channel_owner_room_time",
+            "channel",
+            "owner_account_id",
+            "room_id",
+            "timestamp",
+        ),
     )