fix(providers): remove Qwen provider support

Qwen OAuth flow (portal.qwen.ai) stopped working reliably; drop the
executor, registry entry, OAuth provider/service, token refresh
profile, usage handler, and related test coverage and baselines.

open-sse/index.js

@@ -47,7 +47,6 @@ export {
   refreshAccessToken,
   refreshClaudeOAuthToken,
   refreshGoogleToken,
-  refreshQwenToken,
   refreshCodexToken,
   refreshIflowToken,
   refreshGitHubToken,