Use native text Close button for sheet toolbars on macOS

Sheet dismiss buttons rendered as an iOS-style circular glass "X" on
macOS 26, which looks foreign on the desktop. Add a shared
sheetCloseToolbarItem helper that renders a native text "Close" button
on macOS while keeping the compact icon-only xmark on iOS/tvOS, and
replace the ~14 duplicated inline close buttons across sheets with it.

Yattee/Views/Video/PlaylistSelectorSheet.swift

@@ -89,22 +89,7 @@ struct PlaylistSelectorSheet: View {
             .navigationBarTitleDisplayMode(.inline)
             #endif
             .toolbar {
-                #if os(macOS)
-                ToolbarItem(placement: .cancellationAction) {
-                    Button(String(localized: "common.close"), role: .cancel) {
-                        dismiss()
-                    }
-                }
-                #else
-                ToolbarItem(placement: .confirmationAction) {
-                    Button(role: .cancel) {
-                        dismiss()
-                    } label: {
-                        Label(String(localized: "common.close"), systemImage: "xmark")
-                            .labelStyle(.iconOnly)
-                    }
-                }
-                #endif
+                sheetCloseToolbarItem { dismiss() }
             }
             #endif
             .sheet(isPresented: $showingNewPlaylist) {

Yattee/Views/Video/VideoInfoView.swift

@@ -1973,14 +1973,7 @@ struct VideoInfoView: View {
                 #endif
                 #if !os(tvOS)
                 .toolbar {
-                    ToolbarItem(placement: .confirmationAction) {
-                        Button(role: .cancel) {
-                            showingCommentsSheet = false
-                        } label: {
-                            Label(String(localized: "common.close"), systemImage: "xmark")
-                                .labelStyle(.iconOnly)
-                        }
-                    }
+                    sheetCloseToolbarItem { showingCommentsSheet = false }
                 }
                 #endif
             }