onboarding+liveactivity+habits: 3 fixes from device feedback (KC-61)

1. Onboarding Habits caption now explicitly mentions the toggles are
   changeable in Settings, not just times/custom reminder.

2. TaskLiveActivity: removed the checkbox-look circle glyph (hourglass
   instead). iOS has no API for an app to block the system's swipe/dismiss
   gesture on a Live Activity -- not attempted. Added a real Stop control via
   a new StopCountdownIntent (LiveActivityIntent, iOS 17+) embedded directly
   in the card (lock screen '×' + Dynamic Island 'Stop Countdown' button) --
   the actual iOS-supported equivalent of 'long press for options', since
   Live Activities don't support notification-style long-press menus.

3. Habit notifications gain 'Not Today' (dismiss only, intentional no-op --
   the lifetime-tally philosophy has no concept of a logged miss) and 'Stop
   Tracking' (destructive-styled; flips the habit's master toggle off and
   cancels every pending notification for that type across all its slots).

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

KisaniCalWidgets/StopCountdownIntent.swift

@@ -0,0 +1,26 @@
+import AppIntents
+import ActivityKit
+
+/// Ends a running task Live Activity directly from its Lock Screen / Dynamic
+/// Island card — no need to open the app. Runs in the widget extension
+/// process (that's how LiveActivityIntent works), so it talks to ActivityKit
+/// directly rather than going through LiveActivityManager (app target only).
+@available(iOS 17.0, *)
+struct StopCountdownIntent: LiveActivityIntent {
+    static var title: LocalizedStringResource = "Stop Countdown"
+    static var description = IntentDescription("Ends this task's live countdown.")
+
+    @Parameter(title: "Task ID")
+    var taskID: String
+
+    init() {}
+    init(taskID: String) { self.taskID = taskID }
+
+    func perform() async throws -> some IntentResult {
+        for activity in Activity<TaskActivityAttributes>.activities
+        where activity.attributes.taskID == taskID {
+            await activity.end(dismissalPolicy: .immediate)
+        }
+        return .result()
+    }
+}

KisaniCalWidgets/TaskLiveActivity.swift

@@ -10,8 +10,8 @@ struct TaskLiveActivity: Widget {
         ActivityConfiguration(for: TaskActivityAttributes.self) { context in
             // ── Lock screen / banner ──
             HStack(spacing: 12) {
-                Image(systemName: context.state.isComplete ? "checkmark.circle.fill" : "circle")
-                    .font(.system(size: 22))
+                Image(systemName: context.state.isComplete ? "checkmark.circle.fill" : "hourglass")
+                    .font(.system(size: 20))
                     .foregroundColor(context.state.isComplete ? .green : accent)
                     .frame(width: 24)
                 VStack(alignment: .leading, spacing: 2) {
@@ -40,6 +40,18 @@ struct TaskLiveActivity: Widget {
                         .frame(width: 92, alignment: .trailing)
                         .fixedSize(horizontal: false, vertical: true)
                 }
+
+                // Explicit stop control — a Live Activity can't be prevented
+                // from being swiped away by the system, so this gives an
+                // intentional, in-card way to end tracking instead.
+                if #available(iOS 17.0, *), !context.state.isComplete {
+                    Button(intent: StopCountdownIntent(taskID: context.attributes.taskID)) {
+                        Image(systemName: "xmark.circle.fill")
+                            .font(.system(size: 18))
+                            .foregroundColor(.white.opacity(0.5))
+                    }
+                    .buttonStyle(.plain)
+                }
             }
             .padding(.leading, 14)
             .padding(.trailing, 10)
@@ -69,6 +81,16 @@ struct TaskLiveActivity: Widget {
                         .font(.system(.callout, design: .monospaced))
                         .lineLimit(1)
                 }
+                DynamicIslandExpandedRegion(.bottom) {
+                    if #available(iOS 17.0, *), !context.state.isComplete {
+                        Button(intent: StopCountdownIntent(taskID: context.attributes.taskID)) {
+                            Label("Stop Countdown", systemImage: "xmark.circle")
+                                .font(.system(.caption, design: .monospaced))
+                        }
+                        .buttonStyle(.plain)
+                        .tint(accent)
+                    }
+                }
             } compactLeading: {
                 Image(systemName: "checklist").foregroundColor(accent)
             } compactTrailing: {