Add Nginx TLS configuration, structured logging, PHP-FPM upstream, and Filebeat integration

- Configure Nginx to use structured JSON access logs and add request ID headers.
- Define upstream pool for PHP-FPM with load-balancing support.
- Integrate Filebeat for log ingestion across Nginx and PHP logs.
- Add `.env.example` and README for local TLS setup guidance.
- Extend Dockerfile with PHP extensions (GD, Redis, etc.) and Composer dependency installs.
- Add custom PHP configuration for Redis-backed session storage.

.env.example

@@ -0,0 +1,20 @@
+## Environment overrides for docker-compose
+
+# Path to the host's Let's Encrypt directory that contains live/<domain>/ certs.
+# This directory is bind-mounted into the Nginx container at /etc/letsencrypt.
+
+# Linux hosts (default)
+LETSENCRYPT_PATH=/etc/letsencrypt
+
+# Windows (Docker Desktop with WSL Ubuntu). Uncomment and adjust distro name if different.
+# LETSENCRYPT_PATH=//wsl$/Ubuntu/etc/letsencrypt
+
+# Notes:
+# - Ensure the following files exist under the path you set:
+#   live/api.truckwash.dk/fullchain.pem
+#   live/api.truckwash.dk/privkey.pem
+#   live/cloud.truckwash.dk/fullchain.pem
+#   live/cloud.truckwash.dk/privkey.pem
+# - If you do not have certs for cloud.truckwash.dk locally, either comment out that
+#   TLS server block in services/nginx/nginx.conf or place a temporary self-signed
+#   cert/key pair at the expected path.