feat(bookstack): add role for self-hosted BookStack deployment

Deploy BookStack with linuxserver.io images behind Traefik, including
Entra ID OIDC SSO support and a daily backup timer.

Stack:
- lscr.io/linuxserver/bookstack:version-v26.03.3
- lscr.io/linuxserver/mariadb:11.4.9
- Traefik labels for websecure entrypoint on internal network
- Healthcheck via mariadb-admin ping (LSIO image lacks healthcheck.sh)

Features:
- Persistent APP_KEY generated on first run, stored in volume dir
- Optional OIDC SSO via Microsoft Entra ID (configurable per-instance)
- Idempotent admin user creation with DB-based existence check
- Daily systemd timer backup (DB dump + uploads tar + APP_KEY)
  with configurable retention

Implementation notes:
- DB queries use --protocol=tcp with the app user because root@localhost
  uses unix_socket auth in the LSIO MariaDB image (no password) and
  root@% does not exist
- docker_container_exec uses argv: (list) instead of command: (string)
  to avoid argument-splitting issues
- Migration-wait task ensures users table exists before admin check,
  since /login returns 200 before Laravel migrations complete
- no_log: true on all tasks that reference DB or admin passwords
- artisan absolute path (/app/www/artisan) because LSIO image WORKDIR
  is not the app directory

Adds bookstack route to DMZ Traefik service registry.

roles/bookstack/templates/docker-compose.yml.j2

@@ -0,0 +1,87 @@
+#---------------------------------------------------------------------#
+#     BookStack - Self-hosted wiki / knowledge base.                  #
+#---------------------------------------------------------------------#
+---
+services:
+  {{ bookstack_service_name }}:
+    image: {{ bookstack_image }}
+    container_name: {{ bookstack_service_name }}
+    restart: unless-stopped
+    environment:
+      PUID: "{{ bookstack_puid }}"
+      PGID: "{{ bookstack_pgid }}"
+      TZ: "{{ bookstack_tz }}"
+      APP_URL: "{{ bookstack_base_url }}"
+      APP_KEY: "{{ bookstack_resolved_app_key }}"
+      DB_HOST: "{{ bookstack_service_name }}-db"
+      DB_PORT: "3306"
+      DB_DATABASE: "{{ bookstack_db_name }}"
+      DB_USERNAME: "{{ bookstack_db_user }}"
+      DB_PASSWORD: "{{ bookstack_db_password }}"
+      MAIL_DRIVER: "{{ bookstack_mail_driver }}"
+      MAIL_HOST: "{{ bookstack_mail_host }}"
+      MAIL_PORT: "{{ bookstack_mail_port }}"
+      MAIL_USERNAME: "{{ bookstack_mail_username }}"
+      MAIL_PASSWORD: "{{ bookstack_mail_password }}"
+      MAIL_ENCRYPTION: "{{ bookstack_mail_encryption }}"
+      MAIL_FROM: "{{ bookstack_mail_from }}"
+      MAIL_FROM_NAME: "{{ bookstack_mail_from_name }}"
+{% if bookstack_oidc_enabled %}
+      AUTH_METHOD: "oidc"
+      AUTH_AUTO_INITIATE: "{{ bookstack_oidc_auto_initiate | string | lower }}"
+      OIDC_NAME: "{{ bookstack_oidc_name }}"
+      OIDC_DISPLAY_NAME_CLAIMS: "name"
+      OIDC_CLIENT_ID: "{{ bookstack_oidc_client_id }}"
+      OIDC_CLIENT_SECRET: "{{ bookstack_oidc_client_secret }}"
+      OIDC_ISSUER: "{{ bookstack_oidc_issuer }}"
+      OIDC_ISSUER_DISCOVER: "true"
+      OIDC_END_SESSION_ENDPOINT: "true"
+      OIDC_ADDITIONAL_SCOPES: "{{ bookstack_oidc_additional_scopes }}"
+      OIDC_USER_TO_GROUPS: "{{ bookstack_oidc_user_to_groups | string | lower }}"
+      OIDC_GROUPS_CLAIM: "{{ bookstack_oidc_groups_claim }}"
+{% endif %}
+    volumes:
+      - {{ bookstack_appdata_dir }}:/config
+    networks:
+      - {{ bookstack_traefik_network }}
+      - internal
+    depends_on:
+      {{ bookstack_service_name }}-db:
+        condition: service_healthy
+    labels:
+      - "traefik.enable=true"
+      - "traefik.docker.network={{ bookstack_traefik_network }}"
+      - "traefik.http.routers.{{ bookstack_service_name }}.rule=Host(`{{ bookstack_domain }}`)"
+      - "traefik.http.routers.{{ bookstack_service_name }}.entrypoints=websecure"
+      - "traefik.http.routers.{{ bookstack_service_name }}.tls=true"
+      - "traefik.http.routers.{{ bookstack_service_name }}.tls.certresolver={{ bookstack_traefik_certresolver }}"
+      - "traefik.http.services.{{ bookstack_service_name }}.loadbalancer.server.port=80"
+
+  {{ bookstack_service_name }}-db:
+    image: {{ bookstack_db_image }}
+    container_name: {{ bookstack_service_name }}-db
+    restart: unless-stopped
+    environment:
+      PUID: "{{ bookstack_puid }}"
+      PGID: "{{ bookstack_pgid }}"
+      TZ: "{{ bookstack_tz }}"
+      MYSQL_ROOT_PASSWORD: "{{ bookstack_db_root_password }}"
+      MYSQL_DATABASE: "{{ bookstack_db_name }}"
+      MYSQL_USER: "{{ bookstack_db_user }}"
+      MYSQL_PASSWORD: "{{ bookstack_db_password }}"
+    volumes:
+      - {{ bookstack_db_data_dir }}:/config
+    networks:
+      - internal
+    healthcheck:
+      test: ["CMD-SHELL", "mariadb-admin ping -h 127.0.0.1 -u root --password=\"$$MYSQL_ROOT_PASSWORD\" --silent"]
+      interval: 10s
+      timeout: 5s
+      retries: 12
+      start_period: 60s
+
+networks:
+  {{ bookstack_traefik_network }}:
+    external: true
+  internal:
+    driver: bridge