3ce12c59fc
Add standard React controlled/uncontrolled component pattern to AbacusReact: - Add `defaultValue` prop to support uncontrolled mode (component owns state) - When `value` is provided, component operates in controlled mode (syncs to prop) - When only `defaultValue` is provided, component operates in uncontrolled mode - Update HelpAbacus to use defaultValue for interactive help This enables interactive abacus in help mode where the component tracks its own state while parent monitors via onValueChange callback. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>