feat: My Tasks widget, event countdown redesign, completed section

- My Tasks widget: today's tasks with interactive check-off (ToggleTaskIntent)
  and a "+" that opens the app's add-task sheet; writes preserve all task
  fields and sync via the App Group.
- Event Countdown: AZURE/AWS-style header (accent name + countdown label +
  percent); tap the label to cycle days → weeks → time remaining.
- Today: collapsible "Completed" archive section below Upcoming.

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

KisaniCalWidgets/EventCountdownWidget.swift

@@ -67,11 +67,25 @@ struct EventQuery: EntityQuery {
 
 // MARK: - Entry
 
+// Tapping the countdown label cycles this unit (shared by all event widgets).
+let countdownUnitKey = "kisani.widget.countdownUnit"   // 0 = days, 1 = weeks, 2 = time
+
+struct CycleCountdownUnitIntent: AppIntent {
+    static var title: LocalizedStringResource = "Change Countdown Unit"
+
+    func perform() async throws -> some IntentResult {
+        let cur = UserDefaults.kisani.integer(forKey: countdownUnitKey)
+        UserDefaults.kisani.set((cur + 1) % 3, forKey: countdownUnitKey)
+        return .result()
+    }
+}
+
 struct EventEntry: TimelineEntry {
     let date: Date
     let eventName: String
     let start: Date
     let target: Date
+    var unitMode: Int = 0   // 0 days, 1 weeks, 2 time
 
     /// Fraction of the countdown window that has elapsed (0…1).
     var progress: Double {
@@ -97,6 +111,30 @@ struct EventEntry: TimelineEntry {
                                    to: cal.startOfDay(for: target)).day ?? 0
         return max(0, d)
     }
+
+    /// Countdown from the current date. Tapping the label cycles the unit:
+    /// days → weeks → time remaining.
+    var timeLeftLabel: String {
+        if target <= date { return "Today" }
+        let cal = Calendar.current
+        switch unitMode {
+        case 1: // weeks
+            let days = cal.dateComponents([.day], from: cal.startOfDay(for: date),
+                                          to: cal.startOfDay(for: target)).day ?? 0
+            if days < 7 { return "< 1 week left" }
+            let weeks = days / 7
+            return "\(weeks) week\(weeks == 1 ? "" : "s") left"
+        case 2: // time remaining (detailed)
+            let c = cal.dateComponents([.day, .hour], from: date, to: target)
+            let days = c.day ?? 0, hours = c.hour ?? 0
+            if days == 0 { return hours <= 0 ? "Due now" : "\(hours) hr left" }
+            return hours > 0 ? "\(days)d, \(hours) hr left" : "\(days) day\(days == 1 ? "" : "s") left"
+        default: // days
+            let days = cal.dateComponents([.day], from: cal.startOfDay(for: date),
+                                          to: cal.startOfDay(for: target)).day ?? 0
+            return "\(days) day\(days == 1 ? "" : "s") left"
+        }
+    }
 }
 
 // MARK: - Provider
@@ -133,7 +171,8 @@ struct EventProvider: AppIntentTimelineProvider {
         }
         // Never let the start sit after the target.
         let start = min(config.startDate, target)
-        return EventEntry(date: .now, eventName: name, start: start, target: target)
+        let mode = UserDefaults.kisani.integer(forKey: countdownUnitKey)
+        return EventEntry(date: .now, eventName: name, start: start, target: target, unitMode: mode)
     }
 }