Audit fixes: lock-screen sync, live notification urgency, batch postpone (KC-31)

- Lock-screen Mark Complete / Snooze now push to iCloud (CloudSyncManager) and
  reload widget timelines, so background completions reach iCloud/Watch/widgets
  immediately instead of waiting for the next app run.
- Notification copy ("Urgent — tap to mark complete" + evening check-in) now uses
  the live computed Matrix quadrant: reschedule snapshots urgent task IDs from
  displayQuadrant and threads them into scheduleTasks/notifBody, instead of the
  stale stored task.quadrant.
- postponeAllOverdue now mirrors single postpone (clears urgencyOverride and
  re-syncs the stored quadrant per task).
- ISSUES.md: added KC-31 (audit), corrected KC-30 (midnight day/week/month/year);
  left #2 (period-notif Settings toggle) and #6 (configurable thresholds/snooze)
  as pending; noted #1 (Move lists 3 quadrants) as intentional KC-25 behavior.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

KisaniCal/Models/TaskItem.swift

@@ -599,6 +599,8 @@ class TaskViewModel: ObservableObject {
             guard let idx = tasks.firstIndex(where: { $0.id == id }) else { continue }
             let base = tasks[idx].dueDate ?? Date()
             tasks[idx].dueDate = Calendar.current.date(byAdding: .day, value: days, to: base)
+            tasks[idx].urgencyOverride = nil               // re-place from the new deadline
+            tasks[idx].quadrant = displayQuadrant(tasks[idx])  // keep color/fallback in sync
         }
         save()
     }