feat: add 5 PM features — custom statuses, Gantt, quick-add, automations, notifications

- Custom workflow statuses: per-project configurable status definitions
  replacing the fixed task_status enum. Each project defines its own
  workflow with drag-to-reorder, color coding, and category mapping.
- Gantt/timeline view: full project roadmap with task bars, dependency
  arrows, milestone diamonds, zoom levels (day/week/month), and drag
  to reschedule.
- Natural-language quick-add: NLP parser extracts dates, priorities,
  projects, labels, and recurrence from free text. Floating bar with
  'n' shortcut and live parsed preview.
- Automation rules: no-code trigger-action system per project. Triggers
  on status change, task creation, due date approaching. Actions set
  status/priority, add labels, create notifications.
- Notification center: in-app bell icon with unread badge, slide-out
  panel, real-time SSE updates, mark read/all read. Replaces raw
  activity feed dropdown.

Schema: adds status_definitions, automation_rules, notifications tables.
Migrations: 0007, 0008, 0009. 41 NLP parser tests pass.

packages/shared/src/constants/index.ts

@@ -1,6 +1,9 @@
 // ── Task ─────────────────────────────────────────────────────────────────────
 
+// @deprecated — task status is now a per-project status_definition row.
+// Kept as the category enum / default fallback only.
 export const TASK_STATUS = ['todo', 'in_progress', 'done', 'cancelled'] as const;
+export const TASK_STATUS_CATEGORY = ['todo', 'in_progress', 'done', 'cancelled'] as const;
 export const TASK_PRIORITY = ['low', 'medium', 'high', 'urgent'] as const;
 
 // ── Habit ────────────────────────────────────────────────────────────────────