Harden iOS app with audit fixes, UI consistency, and sheet race condition fixes

Applies verified fixes from deep audit (concurrency, performance, security,
accessibility), standardizes CRUD form buttons to Add/Save pattern, removes
.drawingGroup() that broke search bar TextFields, and converts vulnerable
.sheet(isPresented:) + if-let patterns to safe presentation to prevent
blank white modals.

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

iosApp/Casera/MyCrib.swift

@@ -10,6 +10,28 @@ import SwiftUI
 import AppIntents
 
 // MARK: - Date Formatting Helper
+
+/// Cached formatters to avoid repeated allocation in widget rendering
+private enum WidgetDateFormatters {
+    static let dateOnly: DateFormatter = {
+        let f = DateFormatter()
+        f.dateFormat = "yyyy-MM-dd"
+        return f
+    }()
+
+    static let iso8601WithFractional: ISO8601DateFormatter = {
+        let f = ISO8601DateFormatter()
+        f.formatOptions = [.withInternetDateTime, .withFractionalSeconds]
+        return f
+    }()
+
+    static let iso8601: ISO8601DateFormatter = {
+        let f = ISO8601DateFormatter()
+        f.formatOptions = [.withInternetDateTime]
+        return f
+    }()
+}
+
 /// Parses date strings in either yyyy-MM-dd or ISO8601 (RFC3339) format
 /// and returns a user-friendly string like "Today" or "in X days"
 private func formatWidgetDate(_ dateString: String) -> String {
@@ -17,20 +39,15 @@ private func formatWidgetDate(_ dateString: String) -> String {
     var date: Date?
 
     // Try parsing as yyyy-MM-dd first
-    let dateOnlyFormatter = DateFormatter()
-    dateOnlyFormatter.dateFormat = "yyyy-MM-dd"
-    date = dateOnlyFormatter.date(from: dateString)
+    date = WidgetDateFormatters.dateOnly.date(from: dateString)
 
     // Try parsing as ISO8601 (RFC3339) if that fails
     if date == nil {
-        let isoFormatter = ISO8601DateFormatter()
-        isoFormatter.formatOptions = [.withInternetDateTime, .withFractionalSeconds]
-        date = isoFormatter.date(from: dateString)
+        date = WidgetDateFormatters.iso8601WithFractional.date(from: dateString)
 
         // Try without fractional seconds
         if date == nil {
-            isoFormatter.formatOptions = [.withInternetDateTime]
-            date = isoFormatter.date(from: dateString)
+            date = WidgetDateFormatters.iso8601.date(from: dateString)
         }
     }
 
@@ -179,9 +196,11 @@ struct Provider: AppIntentTimelineProvider {
         let tasks = CacheManager.getUpcomingTasks()
         let isInteractive = WidgetActionManager.shared.shouldShowInteractiveWidget()
 
-        // Update every 30 minutes (more frequent for interactive widgets)
+        // Use a longer refresh interval during overnight hours (11pm-6am)
         let currentDate = Date()
-        let nextUpdate = Calendar.current.date(byAdding: .minute, value: 30, to: currentDate)!
+        let hour = Calendar.current.component(.hour, from: currentDate)
+        let refreshMinutes = (hour >= 23 || hour < 6) ? 120 : 30
+        let nextUpdate = Calendar.current.date(byAdding: .minute, value: refreshMinutes, to: currentDate)!
         let entry = SimpleEntry(
             date: currentDate,
             configuration: configuration,