Update backend IPs for ComfyUI and Supervisor proxies

- Remove hardcoded default values from compose.yaml
- Backend IPs now managed via environment variables only

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

ai/compose.yaml

@@ -206,7 +206,7 @@ services:
     restart: unless-stopped
     environment:
       TZ: ${TIMEZONE:-Europe/Berlin}
-      COMFYUI_BACKEND_HOST: ${COMFYUI_BACKEND_HOST:-100.121.199.88}
+      COMFYUI_BACKEND_HOST: ${COMFYUI_BACKEND_HOST}
       COMFYUI_BACKEND_PORT: ${COMFYUI_BACKEND_PORT:-8188}
     volumes:
       - ./comfyui-nginx.conf:/etc/nginx/nginx.conf.template:ro
@@ -239,7 +239,7 @@ services:
     restart: unless-stopped
     environment:
       TZ: ${TIMEZONE:-Europe/Berlin}
-      SUPERVISOR_BACKEND_HOST: ${SUPERVISOR_BACKEND_HOST:-100.121.199.88}
+      SUPERVISOR_BACKEND_HOST: ${SUPERVISOR_BACKEND_HOST}
       SUPERVISOR_BACKEND_PORT: ${SUPERVISOR_BACKEND_PORT:-9001}
     volumes:
       - ./supervisor-nginx.conf:/etc/nginx/nginx.conf.template:ro