fix: standardize refresh intervals to 3 seconds across all screens

Per parity decision #4 — both platforms conform to 3-second refresh intervals.
Previously iOS Works was at 2s, Android was at 5s. Now both at 3s.

Screens updated:
- MyTasksScreen: 2s → 3s
- BusinessSelectionScreen: 2s → 3s
- TaskListScreen: 2s → 3s

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

PayfritWorks/Views/BusinessSelectionScreen.swift

@@ -13,7 +13,7 @@ struct BusinessSelectionScreen: View {
     @State private var selectedBusiness: Employment?
     @State private var debugText = ""
 
-    private let refreshTimer = Timer.publish(every: 2, on: .main, in: .common).autoconnect()
+    private let refreshTimer = Timer.publish(every: 3, on: .main, in: .common).autoconnect()
 
     var body: some View {
         NavigationStack {

PayfritWorks/Views/MyTasksScreen.swift

@@ -20,7 +20,7 @@ struct MyTasksScreen: View {
         FilterTab(value: "completed", label: "Done", icon: "checkmark.circle.fill"),
     ]
 
-    private let refreshTimer = Timer.publish(every: 2, on: .main, in: .common).autoconnect()
+    private let refreshTimer = Timer.publish(every: 3, on: .main, in: .common).autoconnect()
 
     var body: some View {
         VStack(spacing: 0) {

PayfritWorks/Views/TaskListScreen.swift

@@ -11,7 +11,7 @@ struct TaskListScreen: View {
     @State private var selectedTask: WorkTask?
     @State private var showingMyTasks = false
 
-    private let refreshTimer = Timer.publish(every: 2, on: .main, in: .common).autoconnect()
+    private let refreshTimer = Timer.publish(every: 3, on: .main, in: .common).autoconnect()
 
     var body: some View {
         ZStack(alignment: .bottomTrailing) {