fix: drain stale futures in __get_prop_handler on batch failure (#1723)

When get_props_async raises (cloud timeout, network error, etc.) the
pending futures registered in self._get_prop_list stay unresolved
forever. Subsequent get_prop_async calls with the same (did, siid, piid)
key reuse the dead future via the cache lookup at the top of
get_prop_async, so the integration never recovers from a single batch
failure until Home Assistant is restarted.

This was reproducible whenever the cloud HTTP request hung past the
caller's wait_for timeout: every later poll for that key returned the
same cancelled-but-still-pending future. Property entities driven by
async_update silently stopped updating with no error in the logs.

Wrap the await in try/except and fall through with results=[]. The
existing fallback loop then drains every key still in props_req with
set_result(None), unblocking awaiters and freeing the cache slot so
the next aggregation cycle starts fresh.

custom_components/xiaomi_home/miot/miot_cloud.py

@@ -755,7 +755,18 @@ class MIoTHttpClient:
         if not props_buffer:
             _LOGGER.error('get prop error, empty request list')
             return False
-        results = await self.get_props_async(props_buffer)
+        try:
+            results = await self.get_props_async(props_buffer)
+        except Exception as err:  # pylint: disable=broad-exception-caught
+            # If the batch request fails (timeout, network error, etc.), the
+            # pending futures in self._get_prop_list would otherwise stay
+            # unresolved forever. Subsequent get_prop_async calls with the
+            # same key reuse the dead future via the cache lookup at the top
+            # of get_prop_async, so the integration would never recover until
+            # restart. Fall through with empty results so the loop below
+            # drains every requested key with set_result(None).
+            _LOGGER.error('get prop batch failed, %s', err)
+            results = []
 
         for result in results:
             if not all(