Add task completion animations, subscription trials, and quiet debug console

- Completion animations: play user-selected animation on task card after completing,
  with DataManager guard to prevent race condition during animation playback.
  Works in both AllTasksView and ResidenceDetailView. Animation preference
  persisted via @AppStorage and configurable from Settings.
- Subscription: add trial fields (trialStart, trialEnd, trialActive) and
  subscriptionSource to model, cross-platform purchase guard, trial banner
  in upgrade prompt, and platform-aware subscription management in profile.
- Analytics: disable PostHog SDK debug logging and remove console print
  statements to reduce debug console noise.
- Documents: remove redundant nested do-catch blocks in ViewModel wrapper.
- Widgets: add debounced timeline reloads and thread-safe file I/O queue.
- Onboarding: fix animation leak on disappear, remove unused state vars.
- Remove unused files (ContentView, StateFlowExtensions, CustomView).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

iosApp/iosApp/Task/TaskFormView.swift

@@ -69,7 +69,7 @@ struct TaskFormView: View {
             // Parse date from string - use effective due date (nextDueDate if set, otherwise dueDate)
             _dueDate = State(initialValue: (task.effectiveDueDate ?? "").toDate() ?? Date())
 
-            _intervalDays = State(initialValue: task.customIntervalDays != nil ? String(task.customIntervalDays!.int32Value) : "")
+            _intervalDays = State(initialValue: task.customIntervalDays.map { "\($0.int32Value)" } ?? "")
             _estimatedCost = State(initialValue: task.estimatedCost != nil ? String(task.estimatedCost!.doubleValue) : "")
         } else {
             _title = State(initialValue: "")
@@ -444,6 +444,11 @@ struct TaskFormView: View {
             isValid = false
         }
 
+        if !intervalDays.isEmpty, Int32(intervalDays) == nil {
+            viewModel.errorMessage = "Custom interval must be a valid number"
+            isValid = false
+        }
+
         return isValid
     }