refactor: replace html textarea with shadcn Textarea component

app/(app)/pastel/batch/page.tsx

@@ -10,6 +10,7 @@ import {
   SelectValue,
 } from '@/components/ui/select';
 import { Input } from '@/components/ui/input';
+import { Textarea } from '@/components/ui/textarea';
 import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card';
 import { PaletteGrid } from '@/components/pastel/PaletteGrid';
 import { ExportMenu } from '@/components/pastel/ExportMenu';
@@ -112,11 +113,11 @@ export default function BatchPage() {
                   Enter colors (one per line or comma-separated). Supports hex format
                 </p>
 
-                <textarea
+                <Textarea
                   value={inputColors}
                   onChange={(e) => setInputColors(e.target.value)}
                   placeholder="#ff0099, #00ff99, #9900ff&#10;#ff5533&#10;#3355ff"
-                  className="w-full h-48 p-3 border border-border rounded-xl bg-input font-mono text-sm focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-primary/50 focus-visible:border-primary/50 transition-all duration-200"
+                  className="h-48 font-mono"
                 />
 
                 <p className="text-xs text-muted-foreground mt-2">