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/mail/tasks/aliases.yml

@@ -1,8 +1,10 @@
 # read-only docker exec always reports changed; changed_when: false suppresses spurious output
+# failed_when: false — postfix-virtual.cf may not exist on first run
 - name: List existing mail aliases
   command: docker exec mailserver setup alias list
   register: mail_alias_list
   changed_when: false
+  failed_when: false
   tags:
     - users