chore: vendor clipboard into go package

packages/tui/clipboard/clipboard_ios.m

@@ -0,0 +1,20 @@
+// Copyright 2021 The golang.design Initiative Authors.
+// All rights reserved. Use of this source code is governed
+// by a MIT license that can be found in the LICENSE file.
+//
+// Written by Changkun Ou <changkun.de>
+
+//go:build ios
+
+#import <UIKit/UIKit.h>
+#import <MobileCoreServices/MobileCoreServices.h>
+
+void clipboard_write_string(char *s) {
+    NSString *value = [NSString stringWithUTF8String:s];
+    [[UIPasteboard generalPasteboard] setString:value];
+}
+
+char *clipboard_read_string() {
+    NSString *str = [[UIPasteboard generalPasteboard] string];
+    return (char *)[str UTF8String];
+}