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/deploy.yml

@@ -0,0 +1,15 @@
+---
+# Lightweight update deploy — runs in ~60s.
+# Use this for every code push after the initial site.yml run.
+#
+# Usage:
+#   ansible-playbook -i inventory.ini deploy.yml --ask-vault-pass
+
+- name: Deploy DRB update
+  hosts: drb
+  become: true
+  vars_files:
+    - vault.yml
+
+  roles:
+    - deploy