Bars widget: app-driven "Track Countdown" with zero config (KC-20)

- Task long-press menu gains Track/Stop Tracking Countdown, storing the
  tracked event id + tracking date in the App Group (CountdownTracker)
  and reloading widget timelines.
- The widget reads the tracked event directly and bypasses its config:
  Mode A (one-off) = tracking date -> event date; Mode B (recurring) =
  previous occurrence -> next occurrence via the task's recurrence rule.
- WidgetTask decodes isRecurring/recurrenceLabel from the shared JSON.
- With nothing tracked, the configured modes remain the fallback.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

KisaniCalWidgets/WidgetData.swift

@@ -10,6 +10,8 @@ struct WidgetTask: Codable, Identifiable {
     let isComplete: Bool
     let quadrant: String   // raw value of Quadrant enum
     let category: String
+    var isRecurring: Bool = false
+    var recurrenceLabel: String? = nil
 
     // Days remaining until due date
     var daysLeft: Int? {
@@ -60,7 +62,8 @@ func loadWidgetTasks() -> [WidgetTask] {
     else { return [] }
     return raw.map {
         WidgetTask(id: $0.id, title: $0.title, dueDate: $0.dueDate,
-                   isComplete: $0.isComplete, quadrant: $0.quadrant, category: $0.category)
+                   isComplete: $0.isComplete, quadrant: $0.quadrant, category: $0.category,
+                   isRecurring: $0.isRecurring ?? false, recurrenceLabel: $0.recurrenceLabel)
     }
 }
 
@@ -72,8 +75,10 @@ private struct RawTask: Codable {
     var isComplete: Bool = false
     var quadrant: String = "Urgent + Important"
     var category: String = "reminder"
+    var isRecurring: Bool? = nil
+    var recurrenceLabel: String? = nil
     enum CodingKeys: String, CodingKey {
-        case id, title, dueDate, isComplete, quadrant, category
+        case id, title, dueDate, isComplete, quadrant, category, isRecurring, recurrenceLabel
     }
 }