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/services/usage.js

@@ -16,7 +16,6 @@ import { getKimiUsage } from "./usage/kimi.js";
 import { getDeepseekUsage } from "./usage/deepseek.js";
 import { resolveQoderCredentials } from "./qoderModels.js";
 import {
-  getQwenUsage,
   getIflowUsage,
   getOllamaUsage,
   getGlmUsage,
@@ -43,7 +42,6 @@ const USAGE_HANDLERS = {
     const resolved = await resolveQoderCredentials(c, c.proxyOptions).catch(() => null);
     return getQoderUsage(resolved?.accessToken || c.accessToken, c.proxyOptions);
   },
-  qwen: (c) => getQwenUsage(c.accessToken, c.providerSpecificData),
   iflow: (c) => getIflowUsage(c.accessToken),
   ollama: (c) => getOllamaUsage(c.apiKey, c.providerSpecificData, c.proxyOptions),
   glm: (c) => getGlmUsage(c.apiKey, c.provider, c.proxyOptions),