Make source add/edit forms feel native on macOS

Use grouped Form style with LabeledContent rows and move primary
actions into the sheet toolbar for SMB, WebDAV, Local Folder, Remote
Server and the Edit sheet. iOS and tvOS branches unchanged.

Yattee/Views/Settings/AddSource/AddLocalFolderView.swift

@@ -34,6 +34,9 @@ struct AddLocalFolderView: View {
     // MARK: - Body
 
     var body: some View {
+        #if os(macOS)
+        macOSBody
+        #else
         Form {
             nameSection
             folderSection
@@ -53,8 +56,64 @@ struct AddLocalFolderView: View {
             }
         }
         #endif
+        #endif
     }
 
+    #if os(macOS)
+    private var macOSBody: some View {
+        Form {
+            Section {
+                LabeledContent(String(localized: "sources.field.name")) {
+                    TextField("", text: $name)
+                }
+            } footer: {
+                Text(String(localized: "sources.footer.displayName"))
+                    .font(.callout)
+                    .foregroundStyle(.secondary)
+            }
+
+            Section {
+                LabeledContent(String(localized: "sources.header.folder")) {
+                    HStack {
+                        if let url = selectedFolderURL {
+                            Text(url.path)
+                                .lineLimit(1)
+                                .truncationMode(.middle)
+                                .foregroundStyle(.secondary)
+                                .font(.system(.body, design: .monospaced))
+                        } else {
+                            Text(String(localized: "sources.selectFolder"))
+                                .foregroundStyle(.secondary)
+                        }
+                        Button(String(localized: "sources.selectFolder")) {
+                            selectFolderMacOS()
+                        }
+                    }
+                }
+            } footer: {
+                Text(String(localized: "sources.footer.folder"))
+                    .font(.callout)
+                    .foregroundStyle(.secondary)
+            }
+
+            if let result = testResult {
+                SourceTestResultSection(result: result)
+            }
+        }
+        .formStyle(.grouped)
+        .navigationTitle(String(localized: "sources.addLocalFolder"))
+        .toolbar {
+            ToolbarItem(placement: .confirmationAction) {
+                Button(String(localized: "sources.addSource")) {
+                    addSource()
+                }
+                .disabled(!canAdd)
+                .keyboardShortcut(.defaultAction)
+            }
+        }
+    }
+    #endif
+
     // MARK: - Sections
 
     private var nameSection: some View {