feat: add Hetzner-hosted todo application stack

Implement the server-rendered Go todo application with PostgreSQL persistence, Tailwind styling, health checks, and test coverage.

Provision production and staging infrastructure with OpenTofu, including private networking, static IPs, Object Storage backups, and load balancing.

Configure Rocky Linux hosts with Ansible, rootless Podman, PostgreSQL, WAL-G backup automation, staging restores, and generated inventory.

ansible/roles/app/templates/app-todo.container.j2

@@ -0,0 +1,22 @@
+[Unit]
+Description=Todo web application
+After=network-online.target
+Wants=network-online.target
+
+[Container]
+Image={{ app_image }}
+ContainerName=app-todo
+EnvironmentFile=/home/{{ app_user }}/.config/todo.env
+Network=host
+Pull=never
+NoNewPrivileges=true
+ReadOnly=true
+DropCapability=all
+
+[Service]
+Restart=always
+RestartSec=5
+TimeoutStopSec=15
+
+[Install]
+WantedBy=default.target