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

s3_config.json.template

@@ -0,0 +1,27 @@
+{
+  "_comment": "Template file - use 'op inject' to generate s3_config.json",
+  "identities": [
+    {
+      "name": "anonymous",
+      "actions": [
+        "Read"
+      ]
+    },
+    {
+      "name": "gitea",
+      "credentials": [
+        {
+          "accessKey": "op://TerraphimPlatform/gitea-s3/access-key",
+          "secretKey": "op://TerraphimPlatform/gitea-s3/secret-key"
+        }
+      ],
+      "actions": [
+        "Admin",
+        "Read",
+        "List",
+        "Tagging",
+        "Write"
+      ]
+    }
+  ]
+}