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

frontend/src/components/layout/Layout.tsx

@@ -9,18 +9,18 @@ export default function Layout() {
   const { isConnected } = useConfig()
 
   return (
-    <div className="min-h-screen bg-slate-50 dark:bg-slate-900">
+    <div className="min-h-screen bg-slate-50 dark:bg-slate-900 overflow-x-hidden">
       <div className="flex">
         {/* Sidebar */}
         <Sidebar isOpen={sidebarOpen} onClose={() => setSidebarOpen(false)} />
 
         {/* Main content */}
-        <div className="flex-1 flex flex-col min-h-screen lg:ml-0">
+        <div className="flex-1 min-w-0 flex flex-col min-h-screen lg:ml-0">
           {/* Header */}
           <Header onMenuClick={() => setSidebarOpen(true)} isConnected={isConnected} />
 
           {/* Page content */}
-          <main className="flex-1 p-4 lg:p-6">
+          <main className="flex-1 p-3 sm:p-4 lg:p-6 overflow-x-hidden">
             <Outlet />
           </main>
         </div>

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

frontend/src/pages/Upload.tsx

@@ -264,7 +264,7 @@ export default function Upload() {
   ]
 
   return (
-    <div className="h-[calc(100vh-6rem)] flex flex-col gap-6">
+    <div className="h-[calc(100vh-5rem)] sm:h-[calc(100vh-6rem)] flex flex-col gap-3 sm:gap-6">
       {/* Header */}
       <div className="flex items-center justify-between shrink-0">
         <div className="min-w-0">