fix: wrap iOS 17+ APIs in @available checks for iOS 16 compat

ContentUnavailableView and .symbolEffect(.pulse) require iOS 17+
but deployment target is iOS 16. Wrapped all usages in
if #available(iOS 17.0, *) with VStack-based fallbacks for iOS 16.

Files fixed:
- ScanView.swift (4 ContentUnavailableView + 1 symbolEffect)
- QRScannerView.swift (1 ContentUnavailableView)
- BusinessListView.swift (2 ContentUnavailableView)

PayfritBeacon/Views/BusinessListView.swift

@@ -14,19 +14,51 @@ struct BusinessListView: View {
                 if isLoading {
                     ProgressView("Loading businesses…")
                 } else if let error = errorMessage {
-                    ContentUnavailableView {
+                    if #available(iOS 17.0, *) {
-                        Label("Error", systemImage: "exclamationmark.triangle")
+                        ContentUnavailableView {
-                    } description: {
+                            Label("Error", systemImage: "exclamationmark.triangle")
-                        Text(error)
+                        } description: {
-                    } actions: {
+                            Text(error)
-                        Button("Retry") { Task { await loadBusinesses() } }
+                        } actions: {
+                            Button("Retry") { Task { await loadBusinesses() } }
+                        }
+                    } else {
+                        VStack(spacing: 12) {
+                            Image(systemName: "exclamationmark.triangle")
+                                .font(.system(size: 48))
+                                .foregroundStyle(.orange)
+                            Text("Error")
+                                .font(.headline)
+                            Text(error)
+                                .font(.subheadline)
+                                .foregroundStyle(.secondary)
+                                .multilineTextAlignment(.center)
+                            Button("Retry") { Task { await loadBusinesses() } }
+                                .buttonStyle(.borderedProminent)
+                        }
+                        .padding()
                     }
                 } else if businesses.isEmpty {
-                    ContentUnavailableView(
+                    if #available(iOS 17.0, *) {
-                        "No Businesses",
+                        ContentUnavailableView(
-                        systemImage: "building.2",
+                            "No Businesses",
-                        description: Text("You don't have any businesses yet.")
+                            systemImage: "building.2",
-                    )
+                            description: Text("You don't have any businesses yet.")
+                        )
+                    } else {
+                        VStack(spacing: 12) {
+                            Image(systemName: "building.2")
+                                .font(.system(size: 48))
+                                .foregroundStyle(.secondary)
+                            Text("No Businesses")
+                                .font(.headline)
+                            Text("You don't have any businesses yet.")
+                                .font(.subheadline)
+                                .foregroundStyle(.secondary)
+                        }
+                        .frame(maxHeight: .infinity)
+                        .padding()
+                    }
                 } else {
                     List(businesses) { business in
                         Button {

PayfritBeacon/Views/QRScannerView.swift

@@ -141,18 +141,40 @@ struct QRScannerView: View {
         }
     }
 
+    @ViewBuilder
     private var cameraPermissionDenied: some View {
-        ContentUnavailableView {
+        if #available(iOS 17.0, *) {
-            Label("Camera Access Required", systemImage: "camera.fill")
+            ContentUnavailableView {
-        } description: {
+                Label("Camera Access Required", systemImage: "camera.fill")
-            Text("Open Settings and enable camera access for Payfrit Beacon.")
+            } description: {
-        } actions: {
+                Text("Open Settings and enable camera access for Payfrit Beacon.")
-            Button("Open Settings") {
+            } actions: {
-                if let url = URL(string: UIApplication.openSettingsURLString) {
+                Button("Open Settings") {
-                    UIApplication.shared.open(url)
+                    if let url = URL(string: UIApplication.openSettingsURLString) {
+                        UIApplication.shared.open(url)
+                    }
                 }
+                .buttonStyle(.borderedProminent)
             }
-            .buttonStyle(.borderedProminent)
+        } else {
+            VStack(spacing: 16) {
+                Image(systemName: "camera.fill")
+                    .font(.system(size: 48))
+                    .foregroundStyle(.secondary)
+                Text("Camera Access Required")
+                    .font(.headline)
+                Text("Open Settings and enable camera access for Payfrit Beacon.")
+                    .font(.subheadline)
+                    .foregroundStyle(.secondary)
+                    .multilineTextAlignment(.center)
+                Button("Open Settings") {
+                    if let url = URL(string: UIApplication.openSettingsURLString) {
+                        UIApplication.shared.open(url)
+                    }
+                }
+                .buttonStyle(.borderedProminent)
+            }
+            .padding()
         }
     }
 

PayfritBeacon/Views/ScanView.swift

@@ -129,27 +129,62 @@ struct ScanView: View {
         .padding()
     }
 
+    @ViewBuilder
     private var selectServicePointPrompt: some View {
-        ContentUnavailableView(
+        if #available(iOS 17.0, *) {
-            "Select a Service Point",
+            ContentUnavailableView(
-            systemImage: "mappin.and.ellipse",
+                "Select a Service Point",
-            description: Text("Choose or create a service point (table) to provision a beacon for.")
+                systemImage: "mappin.and.ellipse",
-        )
+                description: Text("Choose or create a service point (table) to provision a beacon for.")
+            )
+        } else {
+            VStack(spacing: 12) {
+                Image(systemName: "mappin.and.ellipse")
+                    .font(.system(size: 48))
+                    .foregroundStyle(.secondary)
+                Text("Select a Service Point")
+                    .font(.headline)
+                Text("Choose or create a service point (table) to provision a beacon for.")
+                    .font(.subheadline)
+                    .foregroundStyle(.secondary)
+                    .multilineTextAlignment(.center)
+            }
+            .frame(maxHeight: .infinity)
+            .padding()
+        }
     }
 
     // MARK: - Namespace Loading
 
+    @ViewBuilder
     private var namespaceLoadingView: some View {
         VStack(spacing: 16) {
             if isLoadingNamespace {
                 ProgressView("Allocating beacon namespace…")
             } else {
-                ContentUnavailableView {
+                if #available(iOS 17.0, *) {
-                    Label("Namespace Error", systemImage: "exclamationmark.triangle")
+                    ContentUnavailableView {
-                } description: {
+                        Label("Namespace Error", systemImage: "exclamationmark.triangle")
-                    Text(errorMessage ?? "Failed to allocate beacon namespace")
+                    } description: {
-                } actions: {
+                        Text(errorMessage ?? "Failed to allocate beacon namespace")
-                    Button("Retry") { Task { await loadNamespace() } }
+                    } actions: {
+                        Button("Retry") { Task { await loadNamespace() } }
+                    }
+                } else {
+                    VStack(spacing: 12) {
+                        Image(systemName: "exclamationmark.triangle")
+                            .font(.system(size: 48))
+                            .foregroundStyle(.orange)
+                        Text("Namespace Error")
+                            .font(.headline)
+                        Text(errorMessage ?? "Failed to allocate beacon namespace")
+                            .font(.subheadline)
+                            .foregroundStyle(.secondary)
+                            .multilineTextAlignment(.center)
+                        Button("Retry") { Task { await loadNamespace() } }
+                            .buttonStyle(.borderedProminent)
+                    }
+                    .padding()
                 }
             }
         }
@@ -245,11 +280,26 @@ struct ScanView: View {
             .padding()
 
             if bleManager.discoveredBeacons.isEmpty && !bleManager.isScanning {
-                ContentUnavailableView(
+                if #available(iOS 17.0, *) {
-                    "No Beacons Found",
+                    ContentUnavailableView(
-                    systemImage: "antenna.radiowaves.left.and.right.slash",
+                        "No Beacons Found",
-                    description: Text("Tap Scan to search for nearby beacons")
+                        systemImage: "antenna.radiowaves.left.and.right.slash",
-                )
+                        description: Text("Tap Scan to search for nearby beacons")
+                    )
+                } else {
+                    VStack(spacing: 12) {
+                        Image(systemName: "antenna.radiowaves.left.and.right.slash")
+                            .font(.system(size: 48))
+                            .foregroundStyle(.secondary)
+                        Text("No Beacons Found")
+                            .font(.headline)
+                        Text("Tap Scan to search for nearby beacons")
+                            .font(.subheadline)
+                            .foregroundStyle(.secondary)
+                    }
+                    .frame(maxHeight: .infinity)
+                    .padding()
+                }
             } else {
                 List(bleManager.discoveredBeacons) { beacon in
                     Button {
@@ -274,7 +324,7 @@ struct ScanView: View {
             Image(systemName: "light.beacon.max")
                 .font(.system(size: 64))
                 .foregroundStyle(.orange)
-                .symbolEffect(.pulse)
+                .modifier(PulseEffectModifier())
 
             Text("Beacon is Flashing")
                 .font(.title2.bold())
@@ -768,3 +818,16 @@ struct BeaconRow: View {
     }
 }
 
+// MARK: - iOS 16/17 Compatibility
+
+/// Applies `.symbolEffect(.pulse)` on iOS 17+, no-op on iOS 16
+private struct PulseEffectModifier: ViewModifier {
+    func body(content: Content) -> some View {
+        if #available(iOS 17.0, *) {
+            content.symbolEffect(.pulse)
+        } else {
+            content
+        }
+    }
+}
+