Implement unified network layer with APILayer and migrate iOS ViewModels

Major architectural improvements:
- Created APILayer as single entry point for all network operations
- Integrated cache-first reads with automatic cache updates on mutations
- Migrated all shared Kotlin ViewModels to use APILayer instead of direct API calls
- Migrated iOS ViewModels to wrap shared Kotlin ViewModels with StateFlow observation
- Replaced LookupsManager with DataCache for centralized lookup data management
- Added password reset methods to AuthViewModel
- Added task completion and update methods to APILayer
- Added residence user management methods to APILayer

iOS specific changes:
- Updated LoginViewModel, RegisterViewModel, ProfileViewModel to use shared AuthViewModel
- Updated ContractorViewModel, DocumentViewModel to use shared ViewModels
- Updated ResidenceViewModel to use shared ViewModel and APILayer
- Updated TaskViewModel to wrap shared ViewModel with callback-based interface
- Migrated PasswordResetViewModel and VerifyEmailViewModel to shared AuthViewModel
- Migrated AllTasksView, CompleteTaskView, EditTaskView to use APILayer
- Migrated ManageUsersView, ResidenceDetailView to use APILayer
- Migrated JoinResidenceView to use async/await pattern with APILayer
- Removed LookupsManager.swift in favor of DataCache
- Fixed PushNotificationManager @MainActor issue
- Converted all direct API calls to use async/await with proper error handling

Benefits:
- Reduced code duplication between iOS and Android
- Consistent error handling across platforms
- Automatic cache management for better performance
- Centralized network layer for easier testing and maintenance
- Net reduction of ~700 lines of code through shared logic

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

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

iosApp/iosApp/Residence/JoinResidenceView.swift

@@ -3,13 +3,10 @@ import ComposeApp
 
 struct JoinResidenceView: View {
     @Environment(\.dismiss) private var dismiss
+    @StateObject private var viewModel = ResidenceViewModel()
     let onJoined: () -> Void
 
     @State private var shareCode: String = ""
-    @State private var isJoining = false
-    @State private var errorMessage: String?
-
-    private let residenceApi = ResidenceApi(client: ApiClient_iosKt.createHttpClient())
 
     var body: some View {
         NavigationView {
@@ -24,9 +21,9 @@ struct JoinResidenceView: View {
                                 shareCode = String(newValue.prefix(6))
                             }
                             shareCode = shareCode.uppercased()
-                            errorMessage = nil
+                            viewModel.clearError()
                         }
-                        .disabled(isJoining)
+                        .disabled(viewModel.isLoading)
                 } header: {
                     Text("Enter Share Code")
                 } footer: {
@@ -34,7 +31,7 @@ struct JoinResidenceView: View {
                         .foregroundColor(.secondary)
                 }
 
-                if let error = errorMessage {
+                if let error = viewModel.errorMessage {
                     Section {
                         Text(error)
                             .foregroundColor(.red)
@@ -45,7 +42,7 @@ struct JoinResidenceView: View {
                     Button(action: joinResidence) {
                         HStack {
                             Spacer()
-                            if isJoining {
+                            if viewModel.isLoading {
                                 ProgressView()
                                     .progressViewStyle(CircularProgressViewStyle())
                             } else {
@@ -55,7 +52,7 @@ struct JoinResidenceView: View {
                             Spacer()
                         }
                     }
-                    .disabled(shareCode.count != 6 || isJoining)
+                    .disabled(shareCode.count != 6 || viewModel.isLoading)
                 }
             }
             .navigationTitle("Join Residence")
@@ -65,7 +62,7 @@ struct JoinResidenceView: View {
                     Button("Cancel") {
                         dismiss()
                     }
-                    .disabled(isJoining)
+                    .disabled(viewModel.isLoading)
                 }
             }
         }
@@ -73,29 +70,30 @@ struct JoinResidenceView: View {
 
     private func joinResidence() {
         guard shareCode.count == 6 else {
-            errorMessage = "Share code must be 6 characters"
+            viewModel.errorMessage = "Share code must be 6 characters"
             return
         }
 
-        guard let token = TokenStorage.shared.getToken() else {
-            errorMessage = "Not authenticated"
-            return
-        }
+        Task {
+            // Call the shared ViewModel which uses APILayer
+            await viewModel.sharedViewModel.joinWithCode(code: shareCode)
 
-        isJoining = true
-        errorMessage = nil
-
-        residenceApi.joinWithCode(token: token, code: shareCode) { result, error in
-            if result is ApiResultSuccess<JoinResidenceResponse> {
-                self.isJoining = false
-                self.onJoined()
-                self.dismiss()
-            } else if let errorResult = result as? ApiResultError {
-                self.errorMessage = errorResult.message
-                self.isJoining = false
-            } else if let error = error {
-                self.errorMessage = error.localizedDescription
-                self.isJoining = false
+            // Observe the result
+            for await state in viewModel.sharedViewModel.joinResidenceState {
+                if state is ApiResultSuccess<JoinResidenceResponse> {
+                    await MainActor.run {
+                        viewModel.sharedViewModel.resetJoinResidenceState()
+                        onJoined()
+                        dismiss()
+                    }
+                    break
+                } else if let error = state as? ApiResultError {
+                    await MainActor.run {
+                        viewModel.errorMessage = error.message
+                        viewModel.sharedViewModel.resetJoinResidenceState()
+                    }
+                    break
+                }
             }
         }
     }