aioble/server: Fix _init_capture() guard to match _server_shutdown()

_server_shutdown() guards on _capture_task and deletes all four capture
attributes. _init_capture() guarded on _capture_queue, creating a
mismatch: if _capture_task was missing but _capture_queue persisted
(partial teardown), _init_capture() would no-op and the capture task
would never be recreated, leaving captured writes silently undelivered.

Guard on _capture_task instead, and clean up any orphaned attributes
before reinitializing.

Signed-off-by: Andrew Leech <andrew.leech@planetinnovation.com.au>

Author: pi-anl

micropython/bluetooth/aioble/aioble/server.py

@@ -100,13 +100,21 @@ def write(self, data, send_update=False):
         else:
             ble.gatts_write(self._value_handle, data, send_update)
 
-    # When the a capture-enabled characteristic is created, create the
+    # When a capture-enabled characteristic is created, create the
     # necessary events (if not already created).
+    # Guard on _capture_task (not _capture_queue) to match _server_shutdown()
+    # which guards on _capture_task. This ensures partial teardown (task gone
+    # but queue remains) self-heals instead of silently no-oping.
     @staticmethod
     def _init_capture():
-        if hasattr(BaseCharacteristic, "_capture_queue"):
+        if hasattr(BaseCharacteristic, "_capture_task"):
             return
-
+        # Clean up any partial state from incomplete shutdown
+        for attr in ("_capture_queue", "_capture_write_event", "_capture_consumed_event"):
+            try:
+                delattr(BaseCharacteristic, attr)
+            except AttributeError:
+                pass
         BaseCharacteristic._capture_queue = deque((), _WRITE_CAPTURE_QUEUE_LIMIT)
         BaseCharacteristic._capture_write_event = asyncio.ThreadSafeFlag()
         BaseCharacteristic._capture_consumed_event = asyncio.ThreadSafeFlag()