Add Kiro setup guide

[ayobamiseun]

What changed

• Added a dedicated Kiro setup guide at docs/kiro-setup.md.
• Updated the README Kiro section to point to the new guide.
• Clarified the supported Kiro install paths for this repo's skills: individual GitHub imports, workspace skills under .kiro/skills/, and global skills under ~/.kiro/skills/.

Why

The README mentioned Kiro, but it did not have a dedicated setup guide like the other supported tools. Kiro also has a few important details worth documenting clearly: GitHub imports target an individual skill folder or SKILL.md, workspace and global skills use different directories, and project-specific guidance belongs in Kiro steering rather than copying this repo's root AGENTS.md.

What was implemented

• Documented how to import individual skills through Kiro's Agent Steering & Skills panel.
• Added workspace and global copy-based setup examples.
• Added a recommended starter skill set.
• Explained how Kiro uses Skills, Steering, and Powers differently.
• Added maintenance notes for refreshing imported skills.

Validation

• node scripts/validate-skills.js
• node scripts/run-evals.js