fix: Make container port match FLASK_PORT for custom port configurations

Previously, the internal container port was hardcoded to 5000, so setting
FLASK_PORT to a different value would break the port mapping and healthcheck.

Credit: Tymo3

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docker-compose.yml

@@ -37,7 +37,7 @@ services:
     container_name: mc-webui
     restart: unless-stopped
     ports:
-      - "${FLASK_PORT:-5000}:5000"
+      - "${FLASK_PORT:-5000}:${FLASK_PORT:-5000}"
     volumes:
       - "${MC_CONFIG_DIR}:/root/.config/meshcore:rw"
       - "${MC_ARCHIVE_DIR:-./archive}:/root/.archive/meshcore:rw"
@@ -60,7 +60,7 @@ services:
     networks:
       - meshcore-net
     healthcheck:
-      test: ["CMD", "python", "-c", "import urllib.request; urllib.request.urlopen('http://localhost:5000/api/status')"]
+      test: ["CMD", "python", "-c", "import urllib.request, os; urllib.request.urlopen(f'http://localhost:{os.environ.get(\"FLASK_PORT\", \"5000\")}/api/status')"]
       interval: 30s
       timeout: 10s
       retries: 3