feat: Gitea deployment with 1Password and Caddy

Complete infrastructure deployment including:
- Docker Compose templates with 1Password integration (op://)
- Caddy reverse proxy configuration for git.terraphim.cloud
- Automated deployment script (deploy-to-bigbox.sh)
- Comprehensive documentation and deployment article
- Network isolation: Public (Gitea) + Tailscale (Prometheus/S3)
- Security: No hardcoded secrets, all via 1Password

Services deployed:
- Gitea 1.22.6 (Git hosting)
- PostgreSQL 15 (Database)
- SeaweedFS (S3-compatible storage)
- Prometheus (Monitoring)

Excludes:
- docker-compose.yml (contains resolved secrets)
- s3_config.json (contains resolved secrets)
- Data directories (gitea/, postgres/, seaweedfs/)

Refs: Private deployment on bigbox with TerraphimPlatform vault

Caddyfile

@@ -0,0 +1,15 @@
+# Caddyfile for gitea-stack on bigbox
+# This adds Gitea to the existing Caddy instance on bigbox
+# Copy this snippet to the existing Caddy configuration at /etc/caddy/Caddyfile
+# or use 'caddy reload' to add this route to the running Caddy instance
+
+# Gitea Web Interface - Public via terraphim.cloud domain
+git.terraphim.cloud {
+    reverse_proxy localhost:3000
+    
+    # Logging
+    log {
+        output file /var/log/caddy/gitea-access.log
+        format json
+    }
+}