When users set a custom docker compose command without the -p flag,
Docker Compose defaults to using the directory name (code) as the
project name. If the custom command is later removed, Dokploy uses
-p appName, creating a new stack while the old one remains running.
Injecting COMPOSE_PROJECT_NAME=appName into the .env ensures the
project name is always consistent regardless of the command used.
Closes#4019