Feature 05 task 2: Core UI primitives (#34)

Co-authored-by: dev_agent <dev_agent@cubecraftlabs.com>
Co-committed-by: dev_agent <dev_agent@cubecraftlabs.com>

web/src/ui/Button.tsx

@@ -0,0 +1,16 @@
+import type { ComponentPropsWithRef } from 'react'
+import styles from './Button.module.css'
+
+export type ButtonVariant = 'primary' | 'outline' | 'dark'
+
+export type ButtonProps = ComponentPropsWithRef<'button'> & {
+  variant?: ButtonVariant
+}
+
+// Pill button. Primary is grape with --on-accent text; outline and dark are the
+// secondary treatments from the handoff. `type` defaults to "button" so a
+// Button inside a form never submits by accident.
+export function Button({ variant = 'primary', type = 'button', className, ...rest }: ButtonProps) {
+  const classes = [styles.button, styles[variant], className].filter(Boolean).join(' ')
+  return <button type={type} className={classes} {...rest} />
+}