Fix missing keepalives in \e prompt loop

[rolandwalker]

Description

Fix missing keepalives in \e prompt loop by passing the inputhook value to handle_editor_command().

Checklist

• I added this contribution to the changelog.md file.
• I added my name to the AUTHORS file (or it's already there).
• To lint and format the code, I ran

  uv run ruff check && uv run ruff format && uv run mypy --install-types .

[github-actions]

Findings: none (no correctness or security issues spotted).

Test gap:

1. mycli/main.py: There’s no test that handle_editor_command() forwards inputhook to PromptSession.prompt(). A small unit test with a mocked PromptSession would prevent regressions around keepalive behavior in the editor loop.

Open questions/assumptions:

• I assumed PromptSession.prompt(inputhook=...) accepts None (current usage elsewhere suggests it does).

If you want, I can draft that test.