Add 1-hour cache timeout and fix pull-to-refresh across iOS

- Add configurable cache timeout (CACHE_TIMEOUT_MS) to DataManager
- Fix cache to work with empty results (contractors, documents, residences)
- Change Documents/Warranties view to use client-side filtering for cache efficiency
- Add pull-to-refresh support for empty state views in ListAsyncContentView
- Fix ContractorsListView to pass forceRefresh parameter correctly
- Fix TaskViewModel loading spinner not stopping after refresh completes
- Remove duplicate cache checks in iOS ViewModels, delegate to Kotlin APILayer

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

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

iosApp/iosApp/Core/AsyncContentView.swift

@@ -223,11 +223,17 @@ struct ListAsyncContentView<T, Content: View, EmptyContent: View>: View {
     var body: some View {
         Group {
             if let errorMessage = errorMessage, items.isEmpty {
-                DefaultErrorView(message: errorMessage, onRetry: onRetry)
-                    .frame(maxWidth: .infinity, maxHeight: .infinity)
+                // Wrap in ScrollView for pull-to-refresh support
+                ScrollView {
+                    DefaultErrorView(message: errorMessage, onRetry: onRetry)
+                        .frame(maxWidth: .infinity, minHeight: UIScreen.main.bounds.height * 0.6)
+                }
             } else if items.isEmpty && !isLoading {
-                emptyContent()
-                    .frame(maxWidth: .infinity, maxHeight: .infinity)
+                // Wrap in ScrollView for pull-to-refresh support
+                ScrollView {
+                    emptyContent()
+                        .frame(maxWidth: .infinity, minHeight: UIScreen.main.bounds.height * 0.6)
+                }
             } else {
                 content(items)
             }