Build 60: Scan-to-pay gets a Scan | My Code toggle, yellow QR, native share

Cash App-style scan screen: a segmented Scan | My Code control (new w::segmented)
over either the camera or your own payment QR. My Code shows the @handle above a
big nprofile QR with the Goblin mark nested in a YELLOW center (was white — same
19% footprint, yellow reads as light to a scanner so the High-ECC recovery is
unchanged), and a native Share button. Added share_text to PlatformCallbacks
(Android ACTION_SEND text/plain via a new shareText JNI method; desktop falls
back to clipboard) to share the npub + nprofile link.

android/app/src/main/java/mw/gri/android/MainActivity.java

@@ -510,6 +510,15 @@ public class MainActivity extends GameActivity {
         startActivity(Intent.createChooser(intent, "Share data"));
     }
 
+    // Called from native code to share plain text (e.g. a payment link) via the
+    // system share sheet.
+    public void shareText(String text) {
+        Intent intent = new Intent(Intent.ACTION_SEND);
+        intent.putExtra(Intent.EXTRA_TEXT, text);
+        intent.setType("text/plain");
+        startActivity(Intent.createChooser(intent, "Share"));
+    }
+
     // Called from native code to play a short "error" haptic (rejected payment).
     public void vibrateError() {
         Vibrator vibrator = (Vibrator) getSystemService(Context.VIBRATOR_SERVICE);