Fix Quick Look preview on iOS

.quickLookPreview() is a macOS-only SwiftUI modifier, so the app target
did not compile for iOS at all. Present QLPreviewController through a
UIViewControllerRepresentable in a sheet instead; clearing previewURL
still triggers cleanup and the review prompt.

Cable/Loads/LoadsView.swift

@@ -220,7 +220,17 @@ struct LoadsView: View {
                 }
             )
         }
-        .quickLookPreview($previewURL)
+        .sheet(
+            isPresented: Binding(
+                get: { previewURL != nil },
+                set: { if !$0 { previewURL = nil } }
+            )
+        ) {
+            if let previewURL {
+                QuickLookPreview(url: previewURL)
+                    .ignoresSafeArea()
+            }
+        }
         .onChange(of: previewURL) { _, newValue in
             if newValue == nil {
                 cleanupPreview()

Cable/Loads/QuickLookPreview.swift

@@ -0,0 +1,48 @@
+//
+//  QuickLookPreview.swift
+//  Cable
+//
+
+import QuickLook
+import SwiftUI
+
+/// Presents a single exported file (PDF or PNG) in Quick Look so the user can
+/// inspect it before sharing.
+///
+/// SwiftUI's `quickLookPreview(_:)` modifier is macOS-only, so iOS wraps
+/// `QLPreviewController` directly.
+struct QuickLookPreview: UIViewControllerRepresentable {
+    let url: URL
+
+    func makeUIViewController(context: Context) -> QLPreviewController {
+        let controller = QLPreviewController()
+        controller.dataSource = context.coordinator
+        return controller
+    }
+
+    func updateUIViewController(_ controller: QLPreviewController, context: Context) {
+        guard context.coordinator.url != url as NSURL else { return }
+        context.coordinator.url = url as NSURL
+        controller.reloadData()
+    }
+
+    func makeCoordinator() -> Coordinator {
+        Coordinator(url: url as NSURL)
+    }
+
+    // MARK: - Coordinator
+
+    final class Coordinator: NSObject, QLPreviewControllerDataSource {
+        var url: NSURL
+
+        init(url: NSURL) {
+            self.url = url
+        }
+
+        func numberOfPreviewItems(in controller: QLPreviewController) -> Int { 1 }
+
+        func previewController(_ controller: QLPreviewController, previewItemAt index: Int) -> QLPreviewItem {
+            url
+        }
+    }
+}