Add residence sharing via .casera files

- Add SharedResidence model and package type detection for .casera files
- Add generateSharePackage API endpoint integration
- Create ResidenceSharingManager for iOS and Android
- Add share button to residence detail screens (owner only)
- Add residence import handling with confirmation dialogs
- Update Quick Look extensions to show house icon for residence packages
- Route .casera imports by type (contractor vs residence)

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

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

iosApp/iosApp/Residence/ResidenceDetailView.swift

@@ -32,7 +32,10 @@ struct ResidenceDetailView: View {
     @State private var showDeleteConfirmation = false
     @State private var isDeleting = false
     @State private var showingUpgradePrompt = false
+    @State private var showShareSheet = false
+    @State private var shareFileURL: URL?
     @StateObject private var subscriptionCache = SubscriptionCacheWrapper.shared
+    @StateObject private var sharingManager = ResidenceSharingManager.shared
 
     @Environment(\.dismiss) private var dismiss
 
@@ -146,6 +149,22 @@ struct ResidenceDetailView: View {
         .sheet(isPresented: $showingUpgradePrompt) {
             UpgradePromptView(triggerKey: "add_11th_task", isPresented: $showingUpgradePrompt)
         }
+        .sheet(isPresented: $showShareSheet) {
+            if let url = shareFileURL {
+                ShareSheet(activityItems: [url])
+            }
+        }
+        // Share error alert
+        .alert("Share Failed", isPresented: .init(
+            get: { sharingManager.errorMessage != nil },
+            set: { if !$0 { sharingManager.resetState() } }
+        )) {
+            Button("OK") {
+                sharingManager.resetState()
+            }
+        } message: {
+            Text(sharingManager.errorMessage ?? "Failed to create share link.")
+        }
 
         // MARK: onChange & lifecycle
         .onChange(of: viewModel.reportMessage) { message in
@@ -336,15 +355,21 @@ private extension ResidenceDetailView {
                 }
                 .disabled(viewModel.isGeneratingReport)
             }
-            
+
+            // Share Residence button (owner only)
             if let residence = viewModel.selectedResidence, isCurrentUserOwner(of: residence) {
                 Button {
-                    showManageUsers = true
+                    shareResidence(residence)
                 } label: {
-                    Image(systemName: "person.2")
+                    if sharingManager.isGeneratingPackage {
+                        ProgressView()
+                    } else {
+                        Image(systemName: "square.and.arrow.up")
+                    }
                 }
+                .disabled(sharingManager.isGeneratingPackage)
             }
-            
+
             Button {
                 // Check LIVE task count before adding
                 let totalTasks = tasksResponse?.columns.reduce(0) { $0 + $1.tasks.count } ?? 0
@@ -357,7 +382,7 @@ private extension ResidenceDetailView {
                 Image(systemName: "plus")
             }
             .accessibilityIdentifier(AccessibilityIdentifiers.Task.addButton)
-            
+
             if let residence = viewModel.selectedResidence, isCurrentUserOwner(of: residence) {
                 Button {
                     showDeleteConfirmation = true
@@ -369,6 +394,15 @@ private extension ResidenceDetailView {
             }
         }
     }
+
+    func shareResidence(_ residence: ResidenceResponse) {
+        Task {
+            if let url = await sharingManager.createShareableFile(residence: residence) {
+                shareFileURL = url
+                showShareSheet = true
+            }
+        }
+    }
 }
 
 // MARK: - Data Loading