refactor(web-app-mediawiki): unify debug & oidc handling via _ensure_require, introduce host-side prep, switch to bind mounts

- Removed obsolete Installation.md, TODO.md, 02_debug.yml, 05_oidc.yml and legacy debug enable/disable tasks
- Added 01_prep.yml to render debug.php/oidc.php on host side before container start
- Introduced _ensure_require.yml for generic require_once management in LocalSettings.php
- Renamed 01_install.yml -> 02_install.yml to align with new numbering
- Updated docker-compose.yml.j2 to bind-mount mw-local into /opt/mw-local
- Adjusted vars/main.yml to define MEDIAWIKI_LOCAL_MOUNT_DIR and MEDIAWIKI_LOCAL_PATH
- Templates debug.php.j2 and oidc.php.j2 now gated by MODE_DEBUG and MEDIAWIKI_OIDC_ENABLED
- main.yml now orchestrates prep, install, debug, extensions, oidc require, admin consistently

Ref: https://chatgpt.com/share/68b57db2-efcc-800f-a733-aca952298437

roles/web-app-mediawiki/tasks/01_prep.yml

@@ -0,0 +1,20 @@
+---
+- name: "PREP | Ensure mw-local mount directory exists on host"
+  file:
+    path: "{{ MEDIAWIKI_LOCAL_MOUNT_DIR }}"
+    state: directory
+    mode: "0755"
+
+- name: "PREP | Render oidc.php (host side)"
+  when: MEDIAWIKI_OIDC_ENABLED | bool
+  template:
+    src: "oidc.php.j2"
+    dest: "{{ MEDIAWIKI_LOCAL_MOUNT_DIR }}/oidc.php"
+    mode: "0644"
+  no_log: "{{ MASK_CREDENTIALS_IN_LOGS | bool }}"
+
+- name: "PREP | Render debug.php (host side, always; content gated by MODE_DEBUG)"
+  template:
+    src: "debug.php.j2"
+    dest: "{{ MEDIAWIKI_LOCAL_MOUNT_DIR }}/debug.php"
+    mode: "0644"