implement multi stopwatch

MultiChrono/AddStopwatchView.swift

@@ -0,0 +1,40 @@
+//
+//  AddStopwatchView.swift
+//  MultiChrono
+//
+//  Created by Beatrice Dellacà on 26/01/26.
+//
+
+import SwiftUI
+
+struct AddStopwatchView: View {
+    @Environment(\.dismiss) var dismiss
+    @State private var name: String = ""
+    var onAdd: (String) -> Void
+    
+    var body: some View {
+        NavigationStack {
+            Form {
+                TextField("Stopwatch Name", text: $name)
+            }
+            .navigationTitle("New Stopwatch")
+            .toolbar {
+                ToolbarItem(placement: .cancellationAction) {
+                    Button("Cancel") {
+                        dismiss()
+                    }
+                }
+                ToolbarItem(placement: .confirmationAction) {
+                    Button("Add") {
+                        onAdd(name.isEmpty ? "Stopwatch" : name)
+                        dismiss()
+                    }
+                }
+            }
+        }
+    }
+}
+
+#Preview {
+    AddStopwatchView(onAdd: { _ in })
+}