Add Gitea Actions runner, ansible-lint CI, vault setup, and fix group_vars layout

- Move group_vars into inventory/ so playbooks can find them (was only
  visible to ad-hoc commands via CWD)
- Add Ansible Vault for sensitive variables (gitea/grafana passwords,
  tokens, db credentials) with vault_password_file outside the repo
- Enable Gitea Actions and deploy act_runner with Docker backend on
  the gitea VM
- Add .gitea/workflows/lint.yml to run ansible-lint on every push
- Set up Gitea → GitHub push mirror (sync_on_commit)
- Fix ansible.cfg stdout_callback for ansible-core 2.20 compatibility
- Add python-psycopg2 to gitea role (required for postgresql modules)
- Add docker to gitea_runner role (required by act_runner at startup)
- Exclude password hashes and VM images from git

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

ansible/roles/gitea/defaults/main.yml

@@ -3,10 +3,10 @@ gitea_http_port: 3000
 gitea_domain: "{{ ansible_host }}"
 gitea_db_name: gitea
 gitea_db_user: gitea
-gitea_db_password: gitea
-gitea_secret_key: "REDACTED_SECRET_KEY"
-gitea_internal_token: "REDACTED_INTERNAL_TOKEN"
+gitea_db_password: "{{ vault_gitea_db_password }}"
+gitea_secret_key: "{{ vault_gitea_secret_key }}"
+gitea_internal_token: "{{ vault_gitea_internal_token }}"
 
 gitea_admin_user: adyrem
-gitea_admin_password: ""      # set in vault or at runtime
-gitea_admin_email: ""         # set in group_vars or vault
+gitea_admin_password: "{{ vault_gitea_admin_password }}"
+gitea_admin_email: "{{ vault_gitea_admin_email }}"