fix: address code review feedback

- Fix incorrect API endpoint paths (removed /api prefix)
- Improve TypeScript strict typing with explicit metadata interfaces
- Update SKILL.md with clear trigger phrases and examples
- Fix README installation path reference
- Add clarification about API URL format (no /api suffix needed)
- Export new metadata type interfaces

packages/skills/gantt/gantt-api.sh

@@ -6,7 +6,7 @@
 set -euo pipefail
 
 # Configuration from environment
-API_URL="${MOSAIC_API_URL:-http://localhost:3000/api}"
+API_URL="${MOSAIC_API_URL:-http://localhost:3000}"
 WORKSPACE_ID="${MOSAIC_WORKSPACE_ID:-}"
 API_TOKEN="${MOSAIC_API_TOKEN:-}"