add Terraform + Ansible infrastructure for GCP deployment

Provisions e2-micro VM (us-east1-b, free tier) with static IP, SSH and
web firewall rules, Docker + Caddy startup script, and IAM bindings for
Firestore and GCS access via ADC. Imports existing drb-calls bucket and
c2-server Firestore database into state. Ansible roles handle first-time
setup (swap, docker group) and all subsequent deploys via rsync + docker
compose, with secrets managed via Ansible Vault. DNS stays on AWS Route 53.

infra/ansible/roles/deploy/templates/Caddyfile.j2

@@ -0,0 +1,13 @@
+# Managed by Ansible — do not edit manually on the server.
+
+api.{{ domain }} {
+  reverse_proxy localhost:8888 {
+    header_up X-Forwarded-For {remote_host}
+  }
+}
+
+app.{{ domain }} {
+  reverse_proxy localhost:3000 {
+    header_up X-Forwarded-For {remote_host}
+  }
+}