W5's apply_update_decky now accepts a forwards_l3 flip on a live
topology only when payload['force'] is true (the unforced flip raises
MutationError to keep half-thinking operators from killing
in-container state). Until this commit there was no UI surface that
could even submit such a flip.
Inspector grows a 'PROMOTE TO GATEWAY' / 'DEMOTE GATEWAY' button when
a (non-observed) decky is selected. The handler:
* On pending topologies → submits via editor.updateDecky immediately.
No confirm dialog; no live containers to disturb.
* On active/degraded topologies → window.confirm() explaining the
destructive base recreate ('In-container state is lost; active
sessions to it drop'), then submits with extras.force=true.
useTopologyEditor.updateDecky grows an optional extras arg that
threads force: true into the queued mutation payload. The pending
CRUD path ignores it (no force needed when no containers exist).
MazeNET.tsx wires a toggleGateway callback that handles the
optimistic local state update, surfaces an enqueue toast on the
active path, and lets the SSE forwarder reconcile when
mutation.applied lands.
