feat: respect PORT env variable for Coolify preview deployments

Nginx now listens on ${PORT} (default 7575) instead of hardcoded 7575,
so Coolify can inject a unique port per preview container. The internal
Next.js server is pinned to port 3000 to avoid conflicting with nginx.

scripts/run.sh

@@ -17,12 +17,14 @@ fi
 # Auth secret is generated every time the container starts as it is required, but not used because we don't need JWTs or Mail hashing
 export AUTH_SECRET=$(openssl rand -base64 32)
 
+export PORT=${PORT:-7575}
+
 # Start nginx proxy
-# 1. Replace the HOSTNAME in the nginx template file
+# 1. Replace the HOSTNAME and PORT in the nginx template file
 # 2. Create the nginx configuration file from the template
 # 3. Start the nginx server
 export HOSTNAME
-envsubst '${HOSTNAME}' < /etc/nginx/templates/nginx.conf > /etc/nginx/nginx.conf
+envsubst '${HOSTNAME} ${PORT}' < /etc/nginx/templates/nginx.conf > /etc/nginx/nginx.conf
 # Start services in the background and store their PIDs
 nginx -g 'daemon off;' &
 NGINX_PID=$!
@@ -36,7 +38,7 @@ else
     REDIS_PID=$!
 fi
 
-node apps/nextjs/server.js &
+PORT=3000 node apps/nextjs/server.js &
 NEXTJS_PID=$!
 
 # Function to handle SIGTERM and shut down services