Fix Qwen OAuth and Ollama models listing

- Add generateUXDesignerPrompt method to QwenOAuthService
- Fix Ollama Cloud listModels to handle multiple response formats
- Improve Ollama models parsing with array/different response structures
- All providers now support UX Designer Prompt feature

app/api/qwen/oauth/device/route.ts

@@ -0,0 +1,50 @@
+import { NextRequest, NextResponse } from "next/server";
+import {
+  QWEN_OAUTH_CLIENT_ID,
+  QWEN_OAUTH_DEVICE_CODE_ENDPOINT,
+  QWEN_OAUTH_SCOPE,
+} from "../../constants";
+
+export async function POST(request: NextRequest) {
+  try {
+    const body = await request.json().catch(() => ({}));
+    const { code_challenge, code_challenge_method } = body || {};
+
+    if (!code_challenge || !code_challenge_method) {
+      return NextResponse.json(
+        { error: "code_challenge and code_challenge_method are required" },
+        { status: 400 }
+      );
+    }
+
+    const response = await fetch(QWEN_OAUTH_DEVICE_CODE_ENDPOINT, {
+      method: "POST",
+      headers: {
+        "Content-Type": "application/x-www-form-urlencoded",
+        Accept: "application/json",
+      },
+      body: new URLSearchParams({
+        client_id: QWEN_OAUTH_CLIENT_ID,
+        scope: QWEN_OAUTH_SCOPE,
+        code_challenge,
+        code_challenge_method,
+      }),
+    });
+
+    const payload = await response.text();
+    if (!response.ok) {
+      return NextResponse.json(
+        { error: "Device authorization failed", details: payload },
+        { status: response.status }
+      );
+    }
+
+    return NextResponse.json(JSON.parse(payload));
+  } catch (error) {
+    console.error("Qwen device authorization failed", error);
+    return NextResponse.json(
+      { error: "Device authorization failed" },
+      { status: 500 }
+    );
+  }
+}