Add support for Helix editor keybindings in the REPL, providing users
with a modern, selection-first modal editing experience as an alternative
to Vim, Emacs, and VSCode keybindings.
Helix Keybindings Integration:
- Add codemirror-helix@^0.5.0 dependency to @strudel/codemirror
- Import and register helix keybindings in keybindings.mjs
- Add 'Helix' option to keybindings selector in Settings UI
- Create comprehensive user documentation at technical-manual/helix.mdx
- Update developer documentation with keybinding integration pattern
The Helix mode provides selection-first editing (select → action) which
differs from Vim's action-motion paradigm, offering an alternative
workflow for modal editing enthusiasts.
Documentation:
- Update CLAUDE.md with Helix support and keybinding addition process
- Create helix.mdx with user-facing documentation and command reference
- Update CHANGELOG.md with December 2025 entry
Testing:
Run `pnpm i` to install new dependencies, then `pnpm dev` to test.
Verify Helix mode works in Settings → Keybindings → Helix.
