Add Kiro support and fix hardcoded path in allowed-tools

[nklmish]

The allowed-tools frontmatter in skills/langfuse/SKILL.md has a hardcoded Claude Code path:

- Read(~/.claude/skills/langfuse/references/**)

This breaks portability. Kiro installs skills into .kiro/skills/, not ~/.claude/skills/, so the path doesn't resolve and reference files can't be read.

The agentskills.io spec recommends using relative paths instead of hardcoding agent-specific directories.

Fix:

- Read(./references/**)

./ resolves relative to the skill's directory (where SKILL.md lives), so it works regardless of where the skill is installed. Verified this doesn't break Claude Code, the ${CLAUDE_SKILL_DIR} mechanism resolves ./ the same way.

README changes:

Added a Kiro installation section with the tested method (git clone + copy to .kiro/skills/). Both project-level and global (~/.kiro/skills/) installation were verified.

Testing done in Kiro IDE:

• Skill discovery: Kiro finds the skill and reads the frontmatter correctly
• Skill activation: Triggers automatically on Langfuse-related prompts
• Reference file resolution: All 6 files under references/ load successfully via the relative path
• CLI data access: npx langfuse-cli api traces list returns real data from Langfuse Cloud
• Global install: Copying to ~/.kiro/skills/ works, skill auto-activates across projects

Branch: kiro-skills