feat: initialize new React application structure with TypeScript, ESLint, and Prettier configurations, while removing legacy files and adding new components and pages for enhanced functionality

src/components/ui/Button.tsx

@@ -0,0 +1,39 @@
+import type { ButtonHTMLAttributes, PropsWithChildren } from 'react';
+
+type ButtonVariant = 'primary' | 'secondary' | 'ghost' | 'danger';
+type ButtonSize = 'md' | 'sm';
+
+interface ButtonProps extends ButtonHTMLAttributes<HTMLButtonElement> {
+  variant?: ButtonVariant;
+  size?: ButtonSize;
+  fullWidth?: boolean;
+  loading?: boolean;
+}
+
+export function Button({
+  children,
+  variant = 'primary',
+  size = 'md',
+  fullWidth = false,
+  loading = false,
+  className = '',
+  disabled,
+  ...rest
+}: PropsWithChildren<ButtonProps>) {
+  const classes = [
+    'btn',
+    `btn-${variant}`,
+    size === 'sm' ? 'btn-sm' : '',
+    fullWidth ? 'btn-full' : '',
+    className
+  ]
+    .filter(Boolean)
+    .join(' ');
+
+  return (
+    <button className={classes} disabled={disabled || loading} {...rest}>
+      {loading && <span className="loading-spinner" aria-hidden="true" />}
+      <span>{children}</span>
+    </button>
+  );
+}