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)

frontend/playwright.config.ts

@@ -1,7 +1,7 @@
 import { defineConfig, devices } from '@playwright/test'
 
 /**
- * Config Playwright pour les tests E2E de Coltura.
+ * Config Playwright pour les tests E2E de Starseed.
  *
  * Pre-requis avant de lancer :
  *   1. Les containers Docker tournent (`make start`)