Add scan progress view

Sources/Photochk/Views/ScanProgressView.swift

@@ -0,0 +1,29 @@
+import SwiftUI
+
+struct ScanProgressView: View {
+    let progress: ScanProgress
+    let onCancel: () -> Void
+
+    var body: some View {
+        VStack(spacing: 14) {
+            if let fraction = progress.fractionCompleted {
+                ProgressView(value: fraction) {
+                    Text(progress.phase.label)
+                } currentValueLabel: {
+                    Text(progress.detailText)
+                        .monospacedDigit()
+                }
+            } else {
+                ProgressView {
+                    Text(progress.phase.label)
+                }
+            }
+
+            Button("中止", role: .cancel, action: onCancel)
+        }
+        .frame(width: 300)
+        .padding(24)
+        .background(.regularMaterial, in: RoundedRectangle(cornerRadius: 14, style: .continuous))
+        .shadow(radius: 20)
+    }
+}