fix(feishu): thread-reply lookup uses the adapter-owned pool too

`_fetch_last_message_in_thread` was the last hot-path `asyncio.to_thread`
in the adapter: after a default-executor teardown (#111020) thread-reply
routing would fail the same way the dedup flush did. Route it through
`_run_blocking` like every other blocking SDK call. The remaining
`to_thread` users (`_load_lark_oapi` at connect/onboarding, the voice
transcode with its file-attachment fallback) are cold or degrade cleanly.

plugins/platforms/feishu/adapter.py

@@ -3576,7 +3576,7 @@ class FeishuAdapter(BasePlatformAdapter):
         try:
             from lark_oapi.api.im.v1 import ListMessageRequest
             request = ListMessageRequest.builder().container_id_type("thread").container_id(thread_id).page_size(1).build()
-            response = await asyncio.to_thread(self._client.im.v1.message.list, request)
+            response = await self._run_blocking(self._client.im.v1.message.list, request)
             if self._response_succeeded(response):
                 items = getattr(getattr(response, "data", None), "items", None)
                 if items and len(items) > 0: