simplified .env configuration with DOMAIN-based defaults and improved docker-compose orchestration

.env.example

@@ -1,4 +1,7 @@
-# --- Application Security ---
+# --- Essential Site Configuration ---
+# Your primary domain (e.g., holy.narl.io). Used to derive ALLOWED_HOSTS, CORS, and CSRF settings.
+DOMAIN="localhost"
+
 # Set to a long, random string in production (e.g. 50+ chars)
 SECRET_KEY="django-insecure-replace-this-in-production"
 
@@ -8,15 +11,12 @@ DEBUG=true
 # Custom URL for the Django Admin interface (e.g., my-secret-admin/)
 ADMIN_URL="admin"
 
-# --- Hosting & Networking ---
-# The primary domain where your app is hosted (e.g., holy.narl.io)
-ALLOWED_HOSTS=localhost,127.0.0.1,backend,holy.narl.io
-
-# CSRF protection: Comma-separated list of trusted origins (MUST start with https:// in production)
-CSRF_TRUSTED_ORIGINS=https://holy.narl.io
-
-# CORS protection: Comma-separated list of allowed origins
-CORS_ALLOWED_ORIGINS=https://holy.narl.io
+# --- Advanced Networking (Optional, derived from DOMAIN if unset) ---
+# ALLOWED_HOSTS=holy.narl.io,another-domain.com
+# CSRF_TRUSTED_ORIGINS=https://holy.narl.io
+# CORS_ALLOWED_ORIGINS=https://holy.narl.io
+# FRONTEND_URL=https://holy.narl.io
+# VITE_API_URL=https://holy.narl.io/api/
 
 # --- SMTP Configuration (Required for Email Verification) ---
 # For development, if EMAIL_HOST is empty, emails are printed to the console.
@@ -32,8 +32,8 @@ EMAIL_HOST_PASSWORD="your-password"
 EMAIL_SKIP_CERT_VERIFICATION=false
 
 # --- Frontend Configuration ---
-# The base URL of the backend API (MUST end with /api/)
-VITE_API_URL=https://holy.narl.io/api/
+# Optional: defaults to ${DOMAIN}/api/ if not set
+# VITE_API_URL=https://holy.narl.io/api/
 VITE_ALLOWED_HOSTS=localhost,holy.narl.io
 
 # --- Impressum / Contact Details (Required for German Law § 5 TMG) ---