chore : rename Coltura to Starseed

- Rename project name across code, configs, docs, dev/prod infra
- Dev: DOCKER_APP_NAME + POSTGRES_DB switched to starseed, containers become php-starseed-fpm / nginx-starseed / starseed-db-1
- Dev: mount nginx.conf on default.conf instead of starseed.conf to avoid alphabetical-order clash with image's default site
- Makefile: export CURRENT_UID/CURRENT_GID at top level so docker compose builds (db-reset etc.) get them
- Prod: image registry path, container_name, volumes, vhost server_name + paths, DATABASE_URL, CORS, CI workflow
- Add doc/prompt-rename-prod.md with the migration runbook for the prod server (DB rename, FS move, vhost, Let's Encrypt)

docker-compose.yml

@@ -41,7 +41,7 @@ services:
       - "8083:80"
     volumes:
       - ./:/var/www/html:ro
-      - ./infra/dev/nginx.conf:/etc/nginx/conf.d/coltura.conf:ro
+      - ./infra/dev/nginx.conf:/etc/nginx/conf.d/default.conf:ro
     restart: unless-stopped
   db:
     image: postgres:16-alpine