fix(deploy): publish on 5910, 8091 is taken on the Swarm ingress

The first real deploy failed with "port '8091' is already in use by
service 'ai-training-lab_ai-lab' as an ingress port". Worth noting the
port answered nothing when probed over HTTP — a Swarm ingress
reservation survives the service behind it being down, so probing is not
a way to find a free port.

5910 is VNC display :10 and sits clear of the 809x web-app block.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

docker-compose.yml

@@ -10,7 +10,11 @@ services:
   remote-control-support:
     image: ${IMAGE:-git.mancinas.io/rmancinas/remote-control-support-webapp:latest}
     ports:
-      - "8091:8080"
+      # 8091 is reserved on the Swarm ingress by ai-training-lab_ai-lab, and a
+      # reservation holds even when nothing is answering on it — so this sits
+      # well clear of the 809x block. 5910 is VNC display :10, which is at least
+      # a hint about what is listening.
+      - "5910:8080"
     environment:
       DB_PATH: /data/rcs.db
       TRUST_PROXY: "true"