Add comprehensive error handling utilities for all screens

Created reusable error handling components that can be used across all
screens in both Android and iOS apps to show retry/cancel dialogs when
network calls fail.

Android Components:
- ApiResultHandler: Composable that automatically handles ApiResult states
  with loading indicators and error dialogs
- HandleErrors(): Extension function for ApiResult to show error dialogs
  for operations that don't return display data
- Updated ResidencesScreen to import ApiResultHandler

iOS Components:
- ViewStateHandler: SwiftUI view that handles loading/error/success states
  with automatic error alerts
- handleErrors(): View modifier for automatic error monitoring
- Both use the existing ErrorAlertModifier for consistent alerts

Documentation:
- Created ERROR_HANDLING.md with comprehensive usage guide
- Includes examples for data loading and create/update/delete operations
- Migration guide for updating existing screens
- Best practices and testing guidelines

These utilities make it easy to add consistent error handling with retry
functionality to any screen that makes network calls, improving the user
experience across the entire app.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

iosApp/iosApp/Helpers/ViewStateHandler.swift

@@ -0,0 +1,112 @@
+import SwiftUI
+
+/// A view that handles loading, error, and success states with automatic error alerts
+///
+/// Example usage:
+/// ```swift
+/// ViewStateHandler(
+///     isLoading: viewModel.isLoading,
+///     error: viewModel.errorMessage,
+///     onRetry: { viewModel.loadData() }
+/// ) {
+///     // Success content
+///     List(items) { item in
+///         Text(item.name)
+///     }
+/// }
+/// ```
+struct ViewStateHandler<Content: View>: View {
+    let isLoading: Bool
+    let error: String?
+    let onRetry: () -> Void
+    let content: Content
+
+    @State private var errorAlert: ErrorAlertInfo? = nil
+
+    init(
+        isLoading: Bool,
+        error: String?,
+        onRetry: @escaping () -> Void,
+        @ViewBuilder content: () -> Content
+    ) {
+        self.isLoading = isLoading
+        self.error = error
+        self.onRetry = onRetry
+        self.content = content()
+    }
+
+    var body: some View {
+        ZStack {
+            if isLoading {
+                ProgressView()
+                    .scaleEffect(1.5)
+            } else {
+                content
+            }
+        }
+        .onChange(of: error) { errorMessage in
+            if let errorMessage = errorMessage, !errorMessage.isEmpty {
+                errorAlert = ErrorAlertInfo(message: errorMessage)
+            }
+        }
+        .errorAlert(
+            error: errorAlert,
+            onRetry: {
+                errorAlert = nil
+                onRetry()
+            },
+            onDismiss: {
+                errorAlert = nil
+            }
+        )
+    }
+}
+
+/// Extension to add automatic error handling to any view
+extension View {
+    /// Monitors an error message and shows error alert when it changes
+    ///
+    /// Example usage:
+    /// ```swift
+    /// Form {
+    ///     // Form fields
+    /// }
+    /// .handleErrors(
+    ///     error: viewModel.errorMessage,
+    ///     onRetry: { viewModel.submitForm() }
+    /// )
+    /// ```
+    func handleErrors(
+        error: String?,
+        onRetry: @escaping () -> Void
+    ) -> some View {
+        modifier(ErrorHandlerModifier(error: error, onRetry: onRetry))
+    }
+}
+
+/// View modifier that handles errors automatically
+private struct ErrorHandlerModifier: ViewModifier {
+    let error: String?
+    let onRetry: () -> Void
+
+    @State private var errorAlert: ErrorAlertInfo? = nil
+
+    func body(content: Content) -> some View {
+        content
+            .onChange(of: error) { errorMessage in
+                if let errorMessage = errorMessage, !errorMessage.isEmpty {
+                    errorAlert = ErrorAlertInfo(message: errorMessage)
+                }
+            }
+            .errorAlert(
+                error: errorAlert,
+                onRetry: {
+                    errorAlert = nil
+                    onRetry()
+                },
+                onDismiss: {
+                    errorAlert = nil
+                }
+            )
+    }
+}