fix: image gate reacts to ComfyUI Interrupt

GateBus.wait() only checked the gate's own Stop flag, so pressing ComfyUI's
Interrupt left the image gate blocked. Add should_cancel to wait() (mirroring
wait_payload) and pass mm.processing_interrupted from gate.py, matching the
text gate.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

gates/gate_bus.py

@@ -27,10 +27,10 @@ class GateBus:
             cls.messages[str(node_id)] = int(message)
 
     @classmethod
-    def wait(cls, node_id, period=0.1):
+    def wait(cls, node_id, period=0.1, should_cancel=None):
         sid = str(node_id)
         while sid not in cls.messages:
-            if cls.cancelled:
+            if cls.cancelled or (should_cancel is not None and should_cancel()):
                 cls.cancelled = False
                 raise GateCancelled()
             time.sleep(period)