feat(F-001): scaffold Next.js 15 project with TypeScript and Tailwind

- Initialize Next.js 15 with App Router and TypeScript strict mode
- Configure Tailwind CSS with shadcn/ui theme system
- Install shadcn/ui components (button, card, input, table, etc.)
- Set up ESLint and Prettier with automatic formatting
- Configure path aliases (@/*) in tsconfig.json
- Create full project structure per CLAUDE.md
- Add health check endpoint at /api/health
- Configure next.config.ts with output: 'standalone' for Docker
- Set up Prisma with placeholder schema
- Configure Vitest (unit) and Playwright (E2E) testing
- Add VS Code settings for consistent development experience

Build verification: TypeScript compilation, ESLint, and production build all pass.

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

src/components/ui/button.tsx

@@ -0,0 +1,57 @@
+import * as React from 'react';
+import { Slot } from '@radix-ui/react-slot';
+import { cva, type VariantProps } from 'class-variance-authority';
+
+import { cn } from '@/lib/utils';
+
+const buttonVariants = cva(
+  'inline-flex items-center justify-center gap-2 whitespace-nowrap rounded-md text-sm font-medium ring-offset-background transition-colors focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring focus-visible:ring-offset-2 disabled:pointer-events-none disabled:opacity-50 [&_svg]:pointer-events-none [&_svg]:size-4 [&_svg]:shrink-0',
+  {
+    variants: {
+      variant: {
+        default: 'bg-primary text-primary-foreground hover:bg-primary/90',
+        destructive:
+          'bg-destructive text-destructive-foreground hover:bg-destructive/90',
+        outline:
+          'border border-input bg-background hover:bg-accent hover:text-accent-foreground',
+        secondary:
+          'bg-secondary text-secondary-foreground hover:bg-secondary/80',
+        ghost: 'hover:bg-accent hover:text-accent-foreground',
+        link: 'text-primary underline-offset-4 hover:underline',
+      },
+      size: {
+        default: 'h-10 px-4 py-2',
+        sm: 'h-9 rounded-md px-3',
+        lg: 'h-11 rounded-md px-8',
+        icon: 'h-10 w-10',
+      },
+    },
+    defaultVariants: {
+      variant: 'default',
+      size: 'default',
+    },
+  }
+);
+
+export interface ButtonProps
+  extends
+    React.ButtonHTMLAttributes<HTMLButtonElement>,
+    VariantProps<typeof buttonVariants> {
+  asChild?: boolean;
+}
+
+const Button = React.forwardRef<HTMLButtonElement, ButtonProps>(
+  ({ className, variant, size, asChild = false, ...props }, ref) => {
+    const Comp = asChild ? Slot : 'button';
+    return (
+      <Comp
+        className={cn(buttonVariants({ variant, size, className }))}
+        ref={ref}
+        {...props}
+      />
+    );
+  }
+);
+Button.displayName = 'Button';
+
+export { Button, buttonVariants };