feat(reui): update ReUI components and documentation

- Added new OIDC configuration options in `.env.example`.
- Expanded documentation in `AGENTS.md` to include OIDC endpoints and admin UI.
- Updated ReUI skill version and component count from 17 to 20 across various documentation files.
- Enhanced `README.md` and other related files to reflect the new component structure and usage guidelines.

Co-authored-by: Cursor <cursoragent@cursor.com>

.env.example

@@ -6,6 +6,9 @@ JWT_SECRET=dev-secret-change-me
 JWT_TTL_HOURS=1
 REFRESH_TTL_DAYS=14
 ISSUER=https://auth.shnt.top
+# OIDC IdP (defaults to ISSUER). Optional PEM PKCS8 RSA key — otherwise auto-generated in DB.
+# OIDC_ISSUER=https://auth.shnt.top
+# OIDC_RSA_PRIVATE_KEY=
 
 # Bootstrap admin (created on first start if DB empty)
 ADMIN_EMAIL=admin@shnt.top