feat(web): add base UI components

- Button with variants (default, destructive, outline, secondary, ghost, link, success)
- Input with consistent styling
- Card with Header, Title, Description, Content, Footer
- Label using Radix UI primitives
- Index file for centralized exports

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/web/components/ui/card.tsx

@@ -0,0 +1,78 @@
+import * as React from 'react';
+import { cn } from '@/lib/utils';
+
+const Card = React.forwardRef<
+  HTMLDivElement,
+  React.HTMLAttributes<HTMLDivElement>
+>(({ className, ...props }, ref) => (
+  <div
+    ref={ref}
+    className={cn(
+      'rounded-lg border bg-card text-card-foreground shadow-sm',
+      className
+    )}
+    {...props}
+  />
+));
+Card.displayName = 'Card';
+
+const CardHeader = React.forwardRef<
+  HTMLDivElement,
+  React.HTMLAttributes<HTMLDivElement>
+>(({ className, ...props }, ref) => (
+  <div
+    ref={ref}
+    className={cn('flex flex-col space-y-1.5 p-6', className)}
+    {...props}
+  />
+));
+CardHeader.displayName = 'CardHeader';
+
+const CardTitle = React.forwardRef<
+  HTMLParagraphElement,
+  React.HTMLAttributes<HTMLHeadingElement>
+>(({ className, ...props }, ref) => (
+  <h3
+    ref={ref}
+    className={cn(
+      'text-2xl font-semibold leading-none tracking-tight',
+      className
+    )}
+    {...props}
+  />
+));
+CardTitle.displayName = 'CardTitle';
+
+const CardDescription = React.forwardRef<
+  HTMLParagraphElement,
+  React.HTMLAttributes<HTMLParagraphElement>
+>(({ className, ...props }, ref) => (
+  <p
+    ref={ref}
+    className={cn('text-sm text-muted-foreground', className)}
+    {...props}
+  />
+));
+CardDescription.displayName = 'CardDescription';
+
+const CardContent = React.forwardRef<
+  HTMLDivElement,
+  React.HTMLAttributes<HTMLDivElement>
+>(({ className, ...props }, ref) => (
+  <div ref={ref} className={cn('p-6 pt-0', className)} {...props} />
+));
+CardContent.displayName = 'CardContent';
+
+const CardFooter = React.forwardRef<
+  HTMLDivElement,
+  React.HTMLAttributes<HTMLDivElement>
+>(({ className, ...props }, ref) => (
+  <div
+    ref={ref}
+    className={cn('flex items-center p-6 pt-0', className)}
+    {...props}
+  />
+));
+CardFooter.displayName = 'CardFooter';
+
+export { Card, CardHeader, CardFooter, CardTitle, CardDescription, CardContent };