refactor(web-app-mybb): remove obsolete Installation.md, introduce schema for secret_pin, and rework task/vars handling

- Removed outdated Installation.md (manual plugin instructions no longer needed)
- Added schema/main.yml with validation for secret_pin
- Added config.php.j2 template to manage DB + admin config
- Refactored tasks/main.yml to deploy config.php instead of legacy docker-compose
- Removed setup-domain.yml (TLS/domain handling moved to core roles)
- Updated docker-compose.yml.j2 to mount config.php and use new vars
- Cleaned up vars/main.yml: standardized MYBB_* variable names, added MYBB_SECRET_PIN, config paths, and container port

See ChatGPT conversation: https://chatgpt.com/share/68b0ae26-93ec-800f-8785-0da7c9303090

roles/web-app-mybb/tasks/main.yml

@@ -1,36 +1,25 @@
-- block:
-  - name: Include dependency 'srv-proxy-core'
-    include_role:
-      name: srv-proxy-core
-    when: run_once_srv_proxy_core is not defined
-  - include_tasks: utils/run_once.yml
-  when: run_once_web_app_mybb is not defined
+- name: "load docker, db and proxy for {{ application_id }}"
+  include_role: 
+    name: cmp-db-docker-proxy
+  vars:
+    docker_compose_flush_handlers: false
+    proxy_extra_configuration: "sub_filter '{{MYBB_DOMAIN}}' '{{ MYBB_DOMAIN }}';"
 
-- name: "include tasks setup-domain.yml with {{ domains | get_domain(application_id) }}"
-  include_tasks: setup-domain.yml
-  loop: "{{ mybb_domains + [source_domain] }}"
-  loop_control:
-    loop_var: domain
-
-- name: "load docker and db for {{ application_id }}"
-  include_role:
-    name: cmp-db-docker
-
-- name: "create {{docker_compose_instance_confd_directory}} and parent directories"
+- name: "create {{ MYBB_NGINX_CONF_DIR_HOST }} and parent directories"
   file:
-    path: "{{docker_compose_instance_confd_directory}}"
+    path: "{{ MYBB_NGINX_CONF_DIR_HOST }}"
     state: directory
     mode: "0755"
     recurse: yes
 
-- name: "create {{docker_compose_instance_confd_defaultconf_file}}"
+- name: "Deploy {{ MYBB_NGINX_DEFAULT_CONF_HOST }}"
   template:
     src: "default.conf.j2"
-    dest: "{{docker_compose_instance_confd_defaultconf_file}}"
+    dest: "{{ MYBB_NGINX_DEFAULT_CONF_HOST }}"
   notify: docker compose up
 
-- name: add docker-compose.yml
+- name: "Deploy {{ MYBB_CONFIG_HOST_PATH }}"
   template:
-    src: "docker-compose.yml.j2"
-    dest: "{{ docker_compose.directories.instance }}docker-compose.yml"
-  notify: docker compose up
+    src: "config.php.j2"
+    dest: "{{ MYBB_CONFIG_HOST_PATH }}"
+    mode: '0644'