fix(cli): correct help tool names for bash output/kill

[Andy963]

What / Why

• ,help currently suggests ,bash_output and ,kill_bash, but the actual internal commands are ,bash.output and ,bash.kill.
• This mismatch causes users to copy/paste from help and immediately hit “unknown command” behavior.

Changes

• Update src/bub/builtin/tools.py help text to list ,bash.output and ,bash.kill.
• Update bash tool docstring to reference bash.output (keeps docs consistent).
• Add regression test tests/test_cli_help.py to ensure help text stays in sync.

Verification

• uv run ruff check .
• uv run mypy src
• uv run pytest -q