Add prod compose and backend production image.

Wire postgres, pgadmin, backend, nginx, and tor with nullcart-style layout; document clearnet and onion hostname env vars for deploy.

.env.example

@@ -16,6 +16,9 @@ FRONTEND_PORT=5173
 
 NODE_ENV=development
 
+CLEARNET_DOMAIN=localhost
+ONION_HOSTNAME=samplexxxxxxxxx.onion
+
 CORS_ORIGINS=http://localhost:5173,http://127.0.0.1:5173
 
 ALTCHA_ENABLED=true
@@ -35,7 +38,7 @@ VALIDATION_UPLOAD_JSON_BODY_PADDING_BYTES=2097152 # 2MiB
 VITE_API_BASE_URL=http://localhost:3000/api
 VITE_CLEARNET_SCHEME=http
 VITE_CLEARNET_DOMAIN=localhost:5173
-VITE_ONION_HOSTNAME=abcdefghijklmnop.onion
+VITE_ONION_HOSTNAME=samplexxxxxxxxx.onion
 VITE_ALTCHA_ENABLED=true
 VITE_ALTCHA_MAX_NUMBER=250000
 VITE_UPLOAD_MAX_QUEUE_SIZE=10