Release v0.3.0

Phase 5 – Export & Polish: Introduce Markdown export, a fast command palette (⌘/Ctrl+K), extended keyboard shortcuts, dark mode, and a finished Settings panel—keyboard-first, “fits your toolchain” UX.

Phase 6 – Distribution: Produce signed installers for Win/macOS/Linux with auto-updates, performance & accessibility audits, comprehensive docs, and 1.0.0 release artifacts—production-ready shipping.