Try "@preact/signals" integration

[subuta]

• Transpile codes for npm distribution.
  • SWC plugin of preact-signals/packages/react at main · XantreGodlike/preact-signals will be applied to sigform with current transpilePackages: ["sigform"] setup and that cause some issue for react signals integration.
• Try this SWC plugin preact-signals/packages/react at main · XantreGodlike/preact-signals for Next.js example
• Simplify APIs by only expose signal instance instead of current value / setValue / mutate