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/WidgetData.swift

@@ -1,5 +1,6 @@
 import Foundation
 import SwiftUI
+import WidgetKit
 
 // Minimal task model shared between widget and main app via App Group
 struct WidgetTask: Codable, Identifiable {
@@ -84,6 +85,59 @@ func nextDueTask(from tasks: [WidgetTask]) -> WidgetTask? {
         .first
 }
 
+private func activeTasksKey() -> String {
+    let uid = UserDefaults.kisani.string(forKey: "kisani.activeUserId") ?? "shared"
+    return "kisani.tasks.v2.\(uid)"
+}
+
+// Tasks due today (incomplete first, then by due time) for the interactive list widget.
+func todayWidgetTasks() -> [WidgetTask] {
+    let cal   = Calendar.current
+    let start = cal.startOfDay(for: Date())
+    let end   = cal.date(byAdding: .day, value: 1, to: start)!
+    return loadWidgetTasks()
+        .filter { t in
+            guard let due = t.dueDate else { return false }
+            return due >= start && due < end
+        }
+        .sorted {
+            if $0.isComplete != $1.isComplete { return !$0.isComplete }
+            return ($0.dueDate ?? .distantFuture) < ($1.dueDate ?? .distantFuture)
+        }
+}
+
+// Toggle a task's completion from the widget. Uses JSONSerialization so ALL task
+// fields are preserved on write (the widget only models a subset of TaskItem).
+func toggleWidgetTaskComplete(id: String) {
+    let key = activeTasksKey()
+    guard let data = UserDefaults.kisani.data(forKey: key),
+          var arr = (try? JSONSerialization.jsonObject(with: data)) as? [[String: Any]]
+    else { return }
+    for i in arr.indices where (arr[i]["id"] as? String) == id {
+        let done = (arr[i]["isComplete"] as? Bool) ?? false
+        arr[i]["isComplete"] = !done
+        if !done {
+            // TaskItem uses the default (deferredToDate) Date strategy → seconds since reference date.
+            arr[i]["completedAt"] = Date().timeIntervalSinceReferenceDate
+        } else {
+            arr[i].removeValue(forKey: "completedAt")
+        }
+    }
+    if let out = try? JSONSerialization.data(withJSONObject: arr) {
+        UserDefaults.kisani.set(out, forKey: key)
+        CloudSyncManager_widgetPush(out, key)
+    }
+    WidgetCenter.shared.reloadAllTimelines()
+}
+
+// The widget extension can't see CloudSyncManager; mirror to iCloud KV store directly.
+private func CloudSyncManager_widgetPush(_ data: Data, _ key: String) {
+    guard data.count < 900_000 else { return }
+    let kv = NSUbiquitousKeyValueStore.default
+    kv.set(data, forKey: key)
+    kv.synchronize()
+}
+
 // Today's task completion: (done, total) for tasks due today.
 func todayTaskCompletion() -> (done: Int, total: Int) {
     let cal   = Calendar.current