marker: drop deleted marker from port NIO cache to stop empty pcap on restart

Deleting a marker while its node was stopped, then starting the node, recreated
an empty pcap. Root cause: delete_marker_capture removed the uBridge filter and
the pcap file but not the marker spec cached on the port NIO (nio.markers) —
the data source _ubridge_apply_markers reads on node start. The stale spec
reinstalled the marker when uBridge came up.

This was a regression from switching stop_marker off update() (which re-sent
the NIO and implicitly refreshed nio.markers) to the fine-grained
node.delete(/markers/{name}) path.

Fix: make the delete port-aware so the compute can locate the NIO. The DELETE
marker route becomes /adapters/{a}/ports/{p}/markers/{name} across all six
node types; the handler resolves the NIO via get_nio and passes it to
delete_marker_capture, which now pops the marker from nio.markers. get_nio
works regardless of uBridge state, so the stopped-node case is covered. The
controller's stop_marker targets the capture side's adapter/port.

tests/controller/test_marker.py

@@ -771,4 +771,6 @@ async def test_stop_marker_deletes_capture_pcap(project):
         capture.delete = AsyncioMagicMock()
         await link.stop_marker("icmp")
 
-    capture.delete.assert_called_once_with("/markers/icmp", params={"link_id": link.id})
+    capture.delete.assert_called_once_with(
+        "/adapters/0/ports/0/markers/icmp", params={"link_id": link.id}
+    )