web-app-mediawiki: template-driven LocalSettings.php + admin automation; compose & config tweaks

Config & features:
- roles/web-app-mediawiki/config/main.yml:
  - Add sitename ('Wiki on {{ PRIMARY_DOMAIN | upper }}') and meta_namespace ('Meta')
  - Enable central_database feature and database service
  - Move volumes under docker.volumes (correct indentation)

Tasks & automation:
- roles/web-app-mediawiki/tasks/main.yml:
  - Avoid immediate compose handler flush (docker_compose_flush_handlers: false), then explicit meta: flush_handlers
  - Deploy templated LocalSettings.php to host path
  - Create admin via maintenance/createAndPromote.php (docker exec, idempotent changed_when/failed_when)

Templates:
- roles/web-app-mediawiki/templates/LocalSettings.php.j2:
  - Set $wgSitename, $wgMetaNamespace, $wgServer from MEDIAWIKI_*
  - DB settings (mysql, host:port, name, user, password)
  - Mail settings (EmergencyContact/PasswordSender)
  - Default skin: vector
  - Load basic extensions (ParserFunctions, Cite)
- roles/web-app-mediawiki/templates/docker-compose.yml.j2:
  - Switch to MEDIAWIKI_* vars, mount LocalSettings.php (ro)
  - Use container_port, include curl healthcheck
  - Fix volumes name to MEDIAWIKI_VOLUME

Vars:
- roles/web-app-mediawiki/vars/main.yml:
  - Restructure with MEDIAWIKI_* (sitename, meta_namespace, URL, image/version/container/volume)
  - Define SETTINGS host/dock paths, container_port, default user (www-data)
  - Admin bootstrap vars (name/password/email)

Misc:
- Add empty schema/main.yml placeholder for future validation

Refs: ChatGPT conversation (2025-08-28, Europe/Berlin). Link: https://chatgpt.com/share/68b0ace6-f8f4-800f-b7a7-a51a6c5260f1

roles/web-app-mediawiki/config/main.yml

@@ -1,16 +1,21 @@
+sitename:       "Wiki on {{ PRIMARY_DOMAIN | upper }}"
+meta_namespace: "Meta"
 server:
   domains:
     canonical:
       - "wiki.{{ PRIMARY_DOMAIN }}"
 docker:
   services:
+    database:
+      enabled:  true
     mediawiki: 
       image:    mediawiki
       version:  latest
       backup:
         no_stop_required: true
       name:     mediawiki
-    volumes:
-      data:     mediawiki_data
+  volumes:
+    data:     mediawiki_data
 features:
   logout: true
+  central_database: true