fix: handle Hunyuan 3D model_glb/model_urls response format from fal.ai

Hunyuan 3D v3.1 returns output in model_glb.url and model_urls.glb.url,
which weren't covered by the existing extraction checks. Also logs result
keys on failure to ease future debugging.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/app/api/generate/providers/fal.ts

@@ -471,6 +471,10 @@ export async function generateWithFalQueue(
         mediaUrl = result.mesh.url;
       } else if (result.glb?.url) {
         mediaUrl = result.glb.url;
+      } else if (result.model_glb?.url) {
+        mediaUrl = result.model_glb.url;
+      } else if (result.model_urls?.glb?.url) {
+        mediaUrl = result.model_urls.glb.url;
       } else if (result.video && result.video.url) {
         mediaUrl = result.video.url;
       } else if (result.images && Array.isArray(result.images) && result.images.length > 0) {
@@ -482,7 +486,7 @@ export async function generateWithFalQueue(
       }
 
       if (!mediaUrl) {
-        console.error(`[API:${requestId}] No media URL found in queue result`);
+        console.error(`[API:${requestId}] No media URL found in queue result. Result keys: ${Object.keys(result).join(", ")}`);
         return {
           success: false,
           error: "No media URL in response",