- Added 'plugins' section in config/main.yml to declare enabled extensions in a structured way
- Introduced new static file 'files/extension_installer_b64.groovy' that decodes Base64 JSON of requested plugins
- Simplified 04_extensions.yml: now builds installer code from static file and removed hardcoded OIDC/LDAP checks
- Dropped redundant XWIKI_EXT_* variables in vars/main.yml
- Added XWIKI_PLUGINS fact to collect enabled plugin items from config/main.yml
This refactor makes extension installation more generic, easier to unit test, and extendable beyond OIDC/LDAP.
See: https://chatgpt.com/share/68ca25e3-cbc4-800f-a45e-2b152369811a