Adds per-port video signal state to the admin Cluster panel:
- New GET /cluster/devices/blackmagic/signal endpoint joins recorders by
node_id+device_index and queries each active capture container's
/capture/status (local: http://recorder-<id>:3001, remote: api_url/
sidecar/<container_id>/status). Returns receiving/connecting/lost/
error/idle/no-recorder per port plus framesReceived and currentFps.
- bmd-card.js render() now accepts portSignals (Map or object) and
overlays a colored dot on each BNC connector with pulse animation
for receiving/connecting states.
- screens-admin.jsx Cluster panel polls the new endpoint every 5s,
feeds the signal map into both the port chips (now show
RECEIVING/CONNECTING/LOST + fps) and the BMD SVG card diagram
rendered below them via a new BmdCardPanel component.
- styles-fixes.css adds bmd-card-* styles for the SVG diagram and
bmd-port-signal --pulse animation.
Heartbeat handler now overrides 172.x docker bridge IPs with the
request's source address when the request itself came from a real LAN.
Adds GET /devices/blackmagic that flattens every node's capabilities so
the recorder UI can show a card picker spanning the whole cluster.
