refactor(deployment): Remove WireGuard VPN dependency and restore public service access

Remove WireGuard integration from production deployment to simplify infrastructure:
- Remove docker-compose-direct-access.yml (VPN-bound services)
- Remove VPN-only middlewares from Grafana, Prometheus, Portainer
- Remove WireGuard middleware definitions from Traefik
- Remove WireGuard IPs (10.8.0.0/24) from Traefik forwarded headers

All monitoring services now publicly accessible via subdomains:
- grafana.michaelschiemer.de (with Grafana native auth)
- prometheus.michaelschiemer.de (with Basic Auth)
- portainer.michaelschiemer.de (with Portainer native auth)

All services use Let's Encrypt SSL certificates via Traefik.

deployment/stacks/traefik/traefik.yml

@@ -64,10 +64,8 @@ providers:
 
 # Forwarded Headers Configuration
 # This ensures Traefik correctly identifies the real client IP
-# Important for VPN access where requests come from WireGuard interface
 forwardedHeaders:
   trustedIPs:
-    - "10.8.0.0/24"      # WireGuard VPN network
     - "127.0.0.1/32"     # Localhost
     - "172.17.0.0/16"    # Docker bridge network
     - "172.18.0.0/16"    # Docker user-defined networks