fix(dingtalk): finalize open streaming cards before disconnect

AI Card "tool progress" cards created with finalize=False were left in
streaming state on DingTalk's UI after a gateway restart because
disconnect() called _streaming_cards.clear() without first closing
them via _close_streaming_siblings.

Move the finalization loop before self._http_client.aclose() so the
HTTP client is still available when the finalize requests are sent.
Adds a regression test that asserts the HTTP client is alive during
finalization.

gateway/platforms/dingtalk.py

@@ -358,6 +358,19 @@ class DingTalkAdapter(BasePlatformAdapter):
             await asyncio.gather(*self._bg_tasks, return_exceptions=True)
             self._bg_tasks.clear()
 
+        # Finalize any open streaming cards before the HTTP client closes so
+        # they don't stay stuck in streaming state on DingTalk's UI after
+        # a gateway restart.  _close_streaming_siblings handles its own
+        # per-card exceptions; the outer try is a safety net for token fetch.
+        for _chat_id in list(self._streaming_cards):
+            try:
+                await self._close_streaming_siblings(_chat_id)
+            except Exception as _exc:
+                logger.debug(
+                    "[%s] Failed to finalize streaming card on disconnect for %s: %s",
+                    self.name, _chat_id, _exc,
+                )
+
         if self._http_client:
             await self._http_client.aclose()
             self._http_client = None