ci(tofu): install community.proxmox/docker for post-create ansible

The proxmox_lxc module's local-exec provisioner runs the install
playbook against the dynamic Proxmox inventory, which needs the
community.proxmox plugin. deploy-infrastructure was the only pipeline
running ansible without installing it. Add community.docker too — most
post-create roles use docker_container.

Surfaced when LXC 250 (registry-mirror) was created cleanly but the
post-create provision failed with "unknown plugin
'community.proxmox.proxmox'".

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.woodpecker/deploy-infrastructure.yml

@@ -98,6 +98,7 @@ steps:
         from_secret: ssh_private_key
     commands:
       - apk add --no-cache git openssh-client ansible curl
+      - ansible-galaxy collection install community.proxmox community.docker
       - mkdir -p ~/.ssh
       - echo "$SSH_PRIVATE_KEY" | base64 -d > ~/.ssh/id_ed25519
       - chmod 600 ~/.ssh/id_ed25519