fix(lnd-ui): align container port across all specs

The LND UI container was unreachable on .228 after the v1.7.43-alpha
deploy because three sources of truth disagreed on which port nginx
listens on inside the container:

  - docker/lnd-ui/nginx.conf        listen 8081
  - docker/lnd-ui/Dockerfile        EXPOSE 8080
  - apps/lnd-ui/manifest.yml        host networking, ports: []
  - scripts/first-boot-containers.sh  -p 8081:8080
  - scripts/deploy-to-target.sh        -p 8081:80     (de-facto)
  - scripts/deploy-tailscale.sh        -p 8081:80
  - scripts/container-specs.sh        SPEC_PORTS=8081:80

Result: podman published host 8081 to container port 80, but no one was
listening on 80 inside, so connections were reset. Canonicalize on
container:80 with host:8081 publish, matching the three deploy paths
already in agreement.

Changes:
  - docker/lnd-ui/nginx.conf: listen 8081 -> listen 80
  - docker/lnd-ui/Dockerfile: EXPOSE 8080 -> EXPOSE 80
  - apps/lnd-ui/manifest.yml: replace host-network (never true) with
    bridge networking and explicit 8081:80 port mapping, correcting a
    documentation-vs-reality mismatch
  - scripts/first-boot-containers.sh: -p 8081:8080 -> -p 8081:80, and
    fix the internal-port comment

Verified on .228 after rebuild: curl http://127.0.0.1:8081/ returns HTTP
200 and the /app/lnd/ host-nginx proxy resolves cleanly.

docker/lnd-ui/Dockerfile

@@ -22,6 +22,6 @@ RUN sed -i 's/^user  nginx;/user  root;/' /etc/nginx/nginx.conf && \
     mkdir -p /var/cache/nginx/client_temp /var/cache/nginx/proxy_temp \
              /var/cache/nginx/fastcgi_temp /var/cache/nginx/uwsgi_temp \
              /var/cache/nginx/scgi_temp
-EXPOSE 8080
+EXPOSE 80
 ENTRYPOINT []
 CMD ["nginx", "-g", "daemon off;"]

docker/lnd-ui/nginx.conf

@@ -1,5 +1,5 @@
 server {
-    listen 8081;
+    listen 80;
     server_name _;
 
     root /usr/share/nginx/html;