- New CalendarPage with daily view (date navigation, slot list) and plans tab
- Route /calendar added in App.tsx
- Sidebar entry added after Proposals
- Daily view: shows time slots with type, status, priority, duration, event data
- Distinguishes real vs virtual (plan) slots visually
- Plans tab: shows schedule plan rules with schedule parameters
- Remove 'story' type from TASK_TYPES in CreateTaskPage.tsx and CreateTaskModal.tsx
- All story/* task types now only creatable via Proposal Accept workflow
- Added comments explaining the restriction
- Add Essential and EssentialType types to frontend types
- Add essentials state and CRUD handlers in ProposalDetailPage
- Display Essential list with type, code, title
- Handle empty state (show message when no essentials)
- Add create/edit modal for Essentials
- Only show edit/delete buttons for open proposals