Initial commit: TaskPool React panel

- React frontend with route-level code splitting
- Backend rebranded from Baihu to TaskPool
- DB brand migration script and local compatibility

web/src/components/ui/textarea.tsx

@@ -0,0 +1,6 @@
+import type { TextareaHTMLAttributes } from 'react'
+import { cn } from '@/lib/utils'
+
+export function Textarea({ className, ...props }: TextareaHTMLAttributes<HTMLTextAreaElement>) {
+  return <textarea {...props} className={cn('ui-control min-h-24 resize-y px-3 py-2', className)} />
+}