v0.9.0

✨ Features

• add undo/redo (ctrl+z / ctrl+y) for node edits, parameter changes, root/scale/tempo, and bank slot clear/cut/paste — each bank grid keeps its own history. Closes #13.
• add color themes: pick a built-in preset with --theme (default, mono, pink) or override individual colors via a palette block in config.json. Closes #18.
• add a [Scoop](https://scoop.sh/) bucket for Windows: scoop bucket add emprcl https://github.com/emprcl/scoop-bucket then scoop install signls. [Docs](https://empr.cl/signls/#installation).

🐛 Bug fixes

• fix mac keyboard layouts using key combos macOS reserves (ctrl+arrows, alt+←/→, f2/f10); remapped to shift/alt+shift+arrows and c/f.
• fix invalid -keyboard/-theme values or an unusable palette color being silently ignored instead of reported.