Phase 0 : scaffolding complet

- Structure monorepo (backend Symfony, frontend React/Vite)
- Docker : FrankenPHP + PostgreSQL/PostGIS + Redis + Traefik labels
- Caddyfile, Dockerfile, .env.example, .gitignore
- MapLibre GL JS + react-map-gl installés
- Roadmap mise à jour

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.env.example

@@ -0,0 +1,15 @@
+# Base de données
+POSTGRES_DB=sargasses
+POSTGRES_USER=app
+POSTGRES_PASSWORD=changeme
+
+# Symfony (copier dans backend/.env.local)
+DATABASE_URL="postgresql://app:changeme@db:5432/sargasses?serverVersion=16&charset=utf8"
+REDIS_URL=redis://redis:6379
+APP_ENV=prod
+APP_SECRET=changeme_generate_with_openssl
+
+# API externes
+SENTINEL_HUB_CLIENT_ID=
+SENTINEL_HUB_CLIENT_SECRET=
+NOAA_GRIB_BASE_URL=https://nomads.ncep.noaa.gov