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>

tests/test_gate_bus.py

@@ -65,3 +65,10 @@ def test_wait_payload_should_cancel_raises():
     gb.GateBus.arm("p")
     with pytest.raises(gb.GateCancelled):
         gb.GateBus.wait_payload("p", should_cancel=lambda: True)
+
+def test_wait_should_cancel_raises():
+    # image gate: ComfyUI Interrupt (should_cancel) must abort the wait too
+    gb.GateBus.arm("7")
+    with pytest.raises(gb.GateCancelled):
+        gb.GateBus.wait("7", should_cancel=lambda: True)
+    assert gb.GateBus.cancelled is False