Add Kimi Code compile/install target

[Aryan Singh K. (aryansk)]

Fixes #2564

Summary

• register Kimi Code as a first-class APM target with .kimi-code/ detection
• compile root instructions through the existing AGENTS family and deploy Kimi-compatible agents and skills to native paths
• support project and user-scope target resolution
• add target detection, active-target, and documentation coverage

Testing

• Not run locally; added focused unit coverage for explicit, configured, and auto-detected Kimi targets.