feat(skills): migrate KiloCoder to config-driven native skills
Replace 269-line custom kilo.js installer with config-driven entry in
platform-codes.yaml targeting .kilocode/skills/ with skill_format: true.
- Add installer config: target_dir, skill_format, template_type, legacy_targets
- Add cleanupKiloModes() to strip BMAD modes from .kilocodemodes on cleanup
- Remove kilo.js from manager.js customFiles and Kilo-specific result handling
- Delete tools/cli/installers/lib/ide/kilo.js
- Add test Suite 22: 11 assertions (config, install, legacy cleanup, modes, reinstall)
- Update migration checklist with verified results
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>