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/providers/registry/qwen.js

@@ -1,33 +0,0 @@
-export default {
-  id: "qwen",
-  hidden: true,
-  priority: 130,
-  alias: "qw",
-  display: {
-    name: "Qwen Code",
-    icon: "psychology",
-    color: "#10B981",
-    website: "https://chat.qwen.ai",
-    notice: {
-      signupUrl: "https://chat.qwen.ai",
-    },
-  },
-  category: "oauth",
-  transport: {
-    baseUrl: "https://portal.qwen.ai/v1/chat/completions",
-  },
-  models: [
-    { id: "qwen3-coder-plus", name: "Qwen3 Coder Plus" },
-    { id: "qwen3-coder-flash", name: "Qwen3 Coder Flash" },
-    { id: "vision-model", name: "Qwen3 Vision Model" },
-    { id: "coder-model", name: "Qwen3.6 Coder Model" },
-  ],
-  oauth: {
-    clientId: "f0304373b74a44d2b584a3fb70ca9e56",
-    deviceCodeUrl: "https://chat.qwen.ai/api/v1/oauth2/device/code",
-    tokenUrl: "https://chat.qwen.ai/api/v1/oauth2/token",
-    scope: "openid profile email model.completion",
-    codeChallengeMethod: "S256",
-    refreshLeadMs: 1200000,
-  },
-};