fix: dump full error response data for gemini image generation to debug 403

backend/server.js

@@ -430,8 +430,12 @@ app.post('/api/sparkplug/generate-images', authenticate, async (req, res) => {
     const generatedUrls = await Promise.all(promises);
     res.json({ images: generatedUrls });
   } catch (err) {
-    // Gemini HTTP errors usually have response.data.error
-    const errorMsg = err.response?.data?.error?.message || err.message;
+    let errorMsg = err.message;
+    if (err.response && err.response.data) {
+      // Just stringify the entire response data so we can see the exact error from Google!
+      errorMsg = typeof err.response.data === 'object' ? JSON.stringify(err.response.data) : err.response.data;
+    }
+    console.error("Gemini Image Gen Error:", errorMsg);
     res.status(500).json({ error: errorMsg });
   }
 });