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.

apps/web/src/components/gantt/gantt-dependency-arrow.tsx

@@ -0,0 +1,50 @@
+import type { TimelineTask } from "./gantt-utils";
+
+export interface TaskPosition {
+  /** Left edge of the task's bar in timeline pixels. */
+  startX: number;
+  /** Right edge of the task's bar in timeline pixels. */
+  endX: number;
+  /** Vertical center of the task's row in pixels. */
+  y: number;
+}
+
+interface GanttDependencyArrowProps {
+  /** The task being depended on (arrow originates at the end of its bar). */
+  fromTask: TimelineTask;
+  /** The blocked task (arrowhead lands at the start of its bar). */
+  toTask: TimelineTask;
+  taskPositions: ReadonlyMap<string, TaskPosition>;
+}
+
+const BEND = 12;
+
+/**
+ * SVG elbow arrow from the end of the blocking task's bar to the start of the
+ * blocked task's bar. Rendered inside the chart's overlay <svg> — the marker
+ * is defined there under the id `gantt-arrow`.
+ */
+export function GanttDependencyArrow({ fromTask, toTask, taskPositions }: GanttDependencyArrowProps) {
+  const from = taskPositions.get(fromTask.id);
+  const to = taskPositions.get(toTask.id);
+  if (!from || !to) return null;
+
+  const x1 = from.endX;
+  const y1 = from.y;
+  // If the target bar starts before the source ends, drop the arrowhead just
+  // past the source end so the elbow path never doubles back on itself.
+  const x2 = Math.max(to.startX, from.endX + BEND);
+  const y2 = to.y;
+  const d = `M ${x1} ${y1} H ${x1 + BEND} L ${x2 - BEND} ${y2} H ${x2}`;
+
+  return (
+    <path
+      d={d}
+      fill="none"
+      stroke="currentColor"
+      strokeWidth={1.5}
+      markerEnd="url(#gantt-arrow)"
+      className="text-muted-foreground/70"
+    />
+  );
+}