Fix fresh-deploy blockers and clean up architecture

- Seed postfix-accounts.cf before mailserver start to satisfy Dovecot's
  requirement for at least one account on first boot
- Add failed_when: false to mail user/alias list tasks (files don't exist
  on first run)
- Add forgejo_runner_version (was undefined); default to 12
- Create /srv/forgejo/data/gitea/conf before deploying app.ini
- Decouple goaccess sync from restic: new enable_goaccess_sync flag with
  its own goaccess_sync_* variables
- Move Docker installation to bootstrap exclusively; rename docker.yml to
  networks.yml (runs docker_network role only)
- Add radicale_password to vault template and setup.sh
- Fix goaccess sync tasks gated on enable_goaccess_sync
- Add upstream bug comment to authorized_key deprecation warning
- Update CLAUDE.md and README.md throughout

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

roles/forgejo/defaults/main.yml

@@ -22,5 +22,6 @@ forgejo_mailer_enabled: false
 # forgejo_smtp_password: defined in vault.yml
 
 # Actions runner
+forgejo_runner_version: "12"
 forgejo_runner_name: default-runner
 forgejo_runner_labels: "docker:docker://node:20-bookworm,ubuntu-latest:docker://ubuntu:latest,ubuntu-22.04:docker://ubuntu:22.04"