Refactor LDAP variable schema to use top-level constant LDAP and nested ALL-CAPS keys.

- Converted group_vars/all/13_ldap.yml from lower-case to ALL-CAPS nested keys.
- Updated all roles, tasks, templates, and filter_plugins to reference LDAP.* instead of ldap.*.
- Fixed Keycloak JSON templates to properly quote Jinja variables.
- Adjusted svc-db-openldap filter plugins and unit tests to handle new LDAP structure.
- Updated integration test to only check uniqueness of TOP-LEVEL ALL-CAPS constants, ignoring nested keys.

See: https://chatgpt.com/share/68b01017-efe0-800f-a508-7d7e2f1c8c8d

roles/web-app-funkwhale/templates/env.j2

@@ -108,12 +108,12 @@ DJANGO_SECRET_KEY={{applications | get_app_conf(application_id, 'credentials.dja
 # Commit: https://gitea.fudaoyuan.icu/Github/funkwhale/commit/4ce46ff2a000646a3dbab80f0ca9fd8d7f8ae24c
 
 LDAP_ENABLED                     =  True
-LDAP_SERVER_URI                  =  "{{ ldap.server.uri }}"
-LDAP_BIND_DN                     =  "{{ ldap.dn.administrator.data }}"
-LDAP_BIND_PASSWORD               =  "{{ ldap.bind_credential }}"
-LDAP_SEARCH_FILTER               =  "{{ ldap.filters.users.login | replace('%' ~ ldap.user.attributes.id, '{0}') }}"
+LDAP_SERVER_URI                  =  "{{ LDAP.SERVER.URI }}"
+LDAP_BIND_DN                     =  "{{ LDAP.DN.ADMINISTRATOR.DATA }}"
+LDAP_BIND_PASSWORD               =  "{{ LDAP.BIND_CREDENTIAL }}"
+LDAP_SEARCH_FILTER               =  "{{ LDAP.FILTERS.USERS.LOGIN | replace('%' ~ LDAP.USER.ATTRIBUTES.ID, '{0}') }}"
 LDAP_START_TLS                   =  False
-LDAP_ROOT_DN                     =  "{{ldap.dn.root}}"
+LDAP_ROOT_DN                     =  "{{ LDAP.DN.ROOT }}"
 LDAP_USER_ATTR_MAP='{"username":"uid","first_name":"givenName","last_name":"sn","email":"mail"}'
 {% endif %}