Complete Phase 2 identity & authentication module:
- Organization CRUD with tree structure (parent_id + materialized path)
- Department CRUD nested under organizations with tree support
- Position CRUD nested under departments
- User management page with table, create/edit modal, role assignment
- Organization architecture page with 3-panel tree layout
- Frontend API layer for orgs/depts/positions
- Sidebar navigation updated with organization menu item
- Fix parse_ttl edge case for strings ending in 'd' (e.g. "invalid")
- API client with axios interceptors: JWT attach + 401 auto-refresh
- Auth store (Zustand): login/logout/loadFromStorage with localStorage
- Login page: gradient background, Ant Design form, error handling
- Home page: dashboard with statistics cards
- App.tsx: PrivateRoute guard, /login route, auth state restoration
- MainLayout: dynamic user display, logout dropdown, menu navigation
- Users API service: CRUD with pagination support
