Revert "feat(CIE): Implement OIDC RP Service with login, callback, and session management"

This reverts commit 5f81d2dcf7.

docs/API_SPEC.md

@@ -35,16 +35,6 @@ Authorization: Bearer <token>
   sends OTP through Mailpit
 - `POST /auth/otp/verify`
   consumes OTP, returns bearer token
-- `POST /auth/cie/start`
-  starts local demo CIE OIDC RP login flow, returns provider `authorization_url`
-  current demo scope: `openid cie_demo`
-- `GET /auth/cie/callback`
-  OIDC redirect URI for provider callback, backend completes token + userinfo flow then redirects frontend
-- `GET /auth/cie/session/{state}`
-  frontend polling endpoint for OIDC login result
-  returns public `status` in `pending | authenticated | failed`
-  internal RP phase exposed separately as `phase`
-  `auth` payload is present only on success
 - `GET /me`
   current user profile, roles, permissions, points
 - `PATCH /me`