feat(cli): add vim mode cursor shape setting

[chrisjcthomas]

Summary

Adds an opt-in general.vimModeCursorShape setting that updates the terminal cursor shape to reflect Vim INSERT vs NORMAL mode.

Details

• adds a useVimCursorShape hook that emits DECSCUSR cursor-shape sequences for INSERT and NORMAL mode
• wires the hook into VimModeProvider so it reacts to both mode transitions and live settings changes
• restores the default cursor shape when the feature is disabled and during terminal cleanup on exit
• regenerates the settings docs and JSON schema for the new setting
• CC @cocosheng-g

Related Issues

Fixes #18390

How to Validate

• Run npx vitest run packages/cli/src/ui/hooks/useVimCursorShape.test.ts packages/cli/src/config/settings-validation.test.ts packages/cli/src/config/settingsSchema.test.ts
• Run npm run docs:settings
• Run npm run schema:settings
• In a DECSCUSR-compatible terminal, enable general.vimMode and general.vimModeCursorShape, then verify INSERT mode shows a bar cursor and NORMAL mode shows a block cursor.

Pre-Merge Checklist

• Updated relevant documentation and README (if needed)
• Added/updated tests (if needed)
• Noted breaking changes (if any)
• Validated on required platforms/methods:
  • MacOS
    • npm run
    • npx
    • Docker
    • Podman
    • Seatbelt
  • Windows
    • npm run
    • npx
    • Docker
  • Linux
    • npm run
    • npx
    • Docker

[google-cla]

Thanks for your pull request! It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

View this failed invocation of the CLA check for more information.

For the most up to date status, view the checks section at the bottom of the pull request.

[chrisjcthomas]

The CLA check appears to be mismatched rather than unsigned.

Evidence:

• My Google Individual CLA is already signed under cobekgn@gmail.com as of March 9, 2026.
• My earlier PR docs: add vi shortcuts and clarify MCP sandbox setup #21679 passed cla/google on April 9, 2026.
• This PR is authored from the same GitHub account (@chrisjcthomas) and commit email (cobekgn@gmail.com).
• I pushed a no-op commit to retrigger the check, and cla/google still failed on the updated head.

If a maintainer can rerun or refresh the CLA association for this PR, I’d appreciate it.