Add lead workflows, PDF signing, AR projects and photo gallery integration

GasTankAR/Views/Leads/Detail/LeadPDFPreview.swift

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+import SwiftUI
+import PDFKit
+
+struct LeadPDFPreview: View {
+    let document: LeadDocument
+    let leadID: String
+    let salesCode: String
+    let repository: any LeadDetailRepository
+    let onLogout: () -> Void
+    var signedURL: URL? = nil
+    @State private var model = LeadFileViewModel()
+    @State private var retryID = 0
+    @State private var showsPreview = false
+    @Environment(\.dismiss) private var dismiss
+
+    var body: some View {
+        NavigationStack {
+            ZStack {
+                if let url = signedURL ?? model.url {
+                    LeadPDFView(url: url)
+                    .fullScreenCover(isPresented: $showsPreview) {
+                        LeadDocumentPreview(url: url)
+                    }
+                } else if let message = model.message {
+                    ContentUnavailableView {
+                        Label("PDF konnte nicht geöffnet werden", systemImage: "doc.badge.ellipsis")
+                    } description: { Text(message) } actions: {
+                        if model.needsLogin {
+                            Button("Erneut anmelden", action: onLogout)
+                        } else if model.allowsRetry {
+                            Button("Erneut versuchen") { retryID += 1 }
+                        }
+                    }
+                } else {
+                    ProgressView("PDF wird heruntergeladen …")
+                }
+            }
+            .navigationTitle(document.title)
+            .navigationBarTitleDisplayMode(.inline)
+            .toolbar {
+                ToolbarItem(placement: .cancellationAction) {
+                    Button(role: .cancel) { dismiss() }
+                        .labelStyle(.iconOnly)
+                }
+                ToolbarItem(placement: .topBarTrailing) {
+                    Button("In Vorschau öffnen", systemImage: "arrow.up.left.and.arrow.down.right") {
+                        showsPreview = true
+                    }
+                    .labelStyle(.iconOnly)
+                    .disabled(signedURL == nil && model.url == nil)
+                }
+            }
+            .task(id: retryID) {
+                guard signedURL == nil else { return }
+                await model.load {
+                    try await DownloadLeadDocumentUseCase(repository: repository)
+                        .execute(document, leadID: leadID, salesCode: salesCode)
+                }
+            }
+        }
+    }
+}