feat: Implement a new Upload page for batch processing team owners, featuring a file dropzone and a new layout.

frontend/src/components/upload/FileDropzone.tsx

@@ -61,7 +61,7 @@ export default function FileDropzone({ onFileSelect, disabled = false, error }:
         onDragOver={handleDragOver}
         onDragLeave={handleDragLeave}
         onDrop={handleDrop}
-        className={`relative border-2 border-dashed rounded-xl p-8 text-center transition-colors ${
+        className={`relative border-2 border-dashed rounded-xl p-5 sm:p-8 text-center transition-colors ${
           disabled
             ? 'border-slate-200 dark:border-slate-700 bg-slate-50 dark:bg-slate-800/50 cursor-not-allowed'
             : isDragging