fix: restore image upload UI in ImageTo3DModal and enforce high quality Meshy generation

backend/server.js

@@ -518,7 +518,10 @@ app.post('/api/sparkplug/generate-3d', authenticate, async (req, res) => {
       image_urls: base64Images,
       enable_pbr: true,
       topology: 'quad',
-      target_polycount: 50000
+      target_polycount: 50000,
+      ai_model: 'meshy-6',
+      hd_texture: true,
+      model_type: 'standard'
     }, {
       headers: {
         'Authorization': `Bearer ${meshyKey}`,

src/components/ImageTo3DModal.tsx

@@ -440,7 +440,7 @@ export const ImageTo3DModal: React.FC<ImageTo3DModalProps> = ({ isOpen, onClose,
                       <span className="text-[10px] text-zinc-500 bg-zinc-800 px-2 py-0.5 rounded-full">Front View</span>
                     </div>
 
-                    <label className="flex-1 flex flex-col items-center justify-center border-2 border-dashed border-zinc-700 hover:border-zinc-500 rounded-xl bg-zinc-900/50 cursor-pointer transition-colors relative overflow-hidden group">
+                    <label className="flex-1 min-h-[160px] flex flex-col items-center justify-center border-2 border-dashed border-zinc-700 hover:border-zinc-500 rounded-xl bg-zinc-900/50 cursor-pointer transition-colors relative overflow-hidden group">
                       <input type="file" ref={fileInputRef} accept="image/png, image/jpeg" className="hidden" onChange={handleImageUpload} />
                       {imagePreview ? (
                         <>