feat: replace Docker named volumes with local bind mounts and add backup script

- docker-compose.yml: sostituisce pgdata/uploads/caddy_data/caddy_config con bind mount su ./data/
- app/public/.gitkeep: crea cartella richiesta dal Dockerfile durante il build
- scripts/backup.sh: backup automatico di DB (pg_dump) e uploads con rotazione 30 giorni
- docs/BACKUP.md: guida completa backup, ripristino e setup cron
- .gitignore: aggiorna con data/ e backups/

docker-compose.yml

@@ -7,7 +7,7 @@ services:
       POSTGRES_PASSWORD: ecommerce_password
       POSTGRES_DB: ecommerce
     volumes:
-      - pgdata:/var/lib/postgresql/data
+      - ./data/db:/var/lib/postgresql/data
     healthcheck:
       test: ["CMD-SHELL", "pg_isready -U ecommerce"]
       interval: 5s
@@ -28,7 +28,7 @@ services:
     expose:
       - "3000"
     volumes:
-      - uploads:/app/public/uploads
+      - ./data/uploads:/app/public/uploads
 
   mailpit:
     image: axllent/mailpit:latest
@@ -44,14 +44,8 @@ services:
       - "443:443"
     volumes:
       - ./Caddyfile:/etc/caddy/Caddyfile:ro
-      - caddy_data:/data
-      - caddy_config:/config
-      - uploads:/srv/uploads
+      - ./data/caddy/data:/data
+      - ./data/caddy/config:/config
+      - ./data/uploads:/srv/uploads
     depends_on:
       - app
-
-volumes:
-  pgdata:
-  caddy_data:
-  caddy_config:
-  uploads: