Introduce a new rms.auth.oauth auth method plugin for OAuth/OIDC code flow with standard provider settings (authorize/token/userinfo URLs, client credentials, scope, redirect URI and extra params). Add server callback handling and OAuth challenge state tracking, UI redirect/error handling, and keep the plugin disabled by default via manifest defaultEnabled=false.
Add the reusable RMS core application (server, web UI, plugins, tests, tools) with generic defaults, GPL licensing, and maintainer context documentation so deployments can consume this repo as software source independent of station-specific overlays.
