Fix PM2 UID type error by using login shell and explicit undefined

- Use su with login shell (-) to ensure clean environment
- Explicitly set uid/gid to undefined in ecosystem config
- This prevents PM2 from trying to parse string UID as integer

The error occurred because PM2 was receiving '1002' as a string
instead of an integer. By using a login shell and explicitly
setting uid/gid to undefined, PM2 won't try to switch users.

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

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

scripts/entrypoint.sh

@@ -92,7 +92,8 @@ fi
 # Start PM2 as the user with HOME environment set
 echo "Starting PM2 as user $user..."
 cd /home/$user/app
-su -c "HOME=/home/$user NODE_ENV=production pm2 start ecosystem.config.js --no-daemon" $user &
+# Use su with login shell to ensure clean environment
+su - $user -c "cd /home/$user/app && NODE_ENV=production pm2 start ecosystem.config.js --no-daemon" &
 
 # Give PM2 time to start
 sleep 5