feat: add Authelia SSO authentication service

- Add Authelia service to NET stack for centralized SSO
- Create configuration.yml with PostgreSQL storage
- Create users_database.yml for file-based user management
- Add authelia database to PostgreSQL init script
- Configure Traefik ForwardAuth middleware
- Add environment variables to arty.yml
- Supports TOTP and WebAuthn 2FA
- Email notifications via Mailpit SMTP relay
- Protected services: netdata, mailpit, scrapy, restic, traefik, dev, n8n, asciinema, coolify

net/authelia/users_database.yml

@@ -0,0 +1,16 @@
+---
+###############################################################
+#                         Users Database                       #
+###############################################################
+
+# This file can be used if you do not have an LDAP set up.
+
+# List of users
+users:
+  valknar:
+    displayname: "Valknar"
+    password: "$argon2id$v=19$m=65536,t=3,p=4$c2FsdHNhbHRzYWx0$4oCb4oCh4oCd4oCi4oCl4oCm"  # CHANGE THIS - use: docker run --rm authelia/authelia:latest authelia crypto hash generate argon2 --password 'yourpassword'
+    email: valknar@pivoine.art
+    groups:
+      - admins
+      - dev