feat(colgrep): add Kimi Code agent integration (#158)

Add --install-kimi / --uninstall-kimi flags following the existing
OpenCode/Codex/Hermes pattern. The installer writes a Kimi Code skill
(SKILL.md with the required YAML frontmatter) to
$KIMI_CODE_HOME/skills/colgrep/ (default ~/.kimi-code/skills/colgrep/),
which Kimi Code CLI auto-discovers and invokes so the agent uses
colgrep as its primary search tool. colgrep --uninstall sweeps the
Kimi skill too.

Co-authored-by: igorcarron <igorcarron@users.noreply.github.com>