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/index.ts

@@ -7,7 +7,9 @@ export {
   createGanttClientFromEnv,
   type GanttClientConfig,
   type Project,
+  type ProjectMetadata,
   type Task,
+  type TaskMetadata,
   type ProjectStatus,
   type TaskStatus,
   type TaskPriority,