feat(mediawiki): Refactor OIDC + debug; install Composer deps in-container; modularize role

Discussion: https://chatgpt.com/share/68b10c0a-c308-800f-93ac-2ffb386cf58b

- Split tasks into 01_install, 02_debug, 03_admin, 04_extensions, 05_oidc.
- Ensure unzip+git+composer on demand in the container; run Composer as www-data with COMPOSER_HOME=/tmp/composer.
- Idempotently unpack/install PluggableAuth & OpenIDConnect; run composer install only if vendor/ is missing.
- Add sanity check for Jumbojett\OpenIDConnectClient.
- Copy oidc.php only when changed and append a single require_once to LocalSettings.php.
- Use REL1_44-compatible numeric array for $wgPluggableAuth_Config; set $wgPluggableAuth_ButtonLabelMessage.
- Debug: add debug.php that logs to STDERR (visible via docker logs); toggle cleanly with MODE_DEBUG.
- Enable OIDC feature in config; add paths/OIDC/extension vars in vars/main.yml.

fix(services): include SYS_SERVICE_GROUP_CLEANUP in StartPre lock (ssd-hdd, docker-hard).

fix(desktop/joomla): simplify MODE_DEBUG templating.

chore: minor cleanups and renames.

roles/web-app-mediawiki/templates/debug.php.j2

@@ -0,0 +1,21 @@
+<?php
+
+$wgShowExceptionDetails   = true;
+$wgShowDBErrorBacktrace   = true;
+$wgShowSQLErrors          = true;
+$wgDevelopmentWarnings    = true;
+
+@ini_set('display_errors', '1');
+@ini_set('display_startup_errors', '1');
+@ini_set('log_errors', '1');
+@ini_set('error_log', '/proc/self/fd/2');
+
+$wgDebugLogGroups = array_merge($wgDebugLogGroups ?? [], [
+    'exception'       => 'php://stderr',
+    'error'           => 'php://stderr',
+    'authentication'  => 'php://stderr',
+    'session'         => 'php://stderr',
+    'resourceloader'  => 'php://stderr',
+    'PluggableAuth'   => 'php://stderr',
+    'OpenIDConnect'   => 'php://stderr',
+]);