Revert mint path to pre-browser PKCE baseline (2e833f2).

Restore HTTP-only SSO OAuth with curl_cffi then std requests fallback;
remove browser PKCE prefer/fallback knobs and mint_from_sso_browser.

oidc_mint/__init__.py

@@ -16,7 +16,6 @@ from .oauth_code import (
     OAuthCodeError,
     SCOPE as CODE_SCOPE,
     mint_from_sso,
-    mint_from_sso_browser,
     normalize_sso_cookie,
     sso_to_token,
 )
@@ -27,7 +26,6 @@ __all__ = [
     "mint_with_browser",
     "shutdown_mint_browsers",
     "mint_from_sso",
-    "mint_from_sso_browser",
     "sso_to_token",
     "normalize_sso_cookie",
     "CLIENT_ID",