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.

src/sse/services/tokenRefresh.js

@@ -11,7 +11,6 @@ import {
   refreshAccessToken as _refreshAccessToken,
   refreshClaudeOAuthToken as _refreshClaudeOAuthToken,
   refreshGoogleToken as _refreshGoogleToken,
-  refreshQwenToken as _refreshQwenToken,
   refreshCodexToken as _refreshCodexToken,
   refreshIflowToken as _refreshIflowToken,
   refreshGitHubToken as _refreshGitHubToken,
@@ -41,9 +40,6 @@ export const refreshClaudeOAuthToken = (refreshToken) =>
 export const refreshGoogleToken = (refreshToken, clientId, clientSecret) =>
   _refreshGoogleToken(refreshToken, clientId, clientSecret, log);
 
-export const refreshQwenToken = (refreshToken) =>
-  _refreshQwenToken(refreshToken, log);
-
 export const refreshCodexToken = (refreshToken) =>
   _refreshCodexToken(refreshToken, log);