fix(mobile-next): 按 B-91 收口 Android 通话视觉打回项

呼出/通话中按钮、计时器、底色、60s 未接与进出场动效对齐视觉规范。

Co-authored-by: Cursor <cursoragent@cursor.com>
Co-authored-by: multica-agent <github@multica.ai>

mobile-next/openim_common/lib/src/utils/utils.dart

@@ -939,7 +939,7 @@ class IMUtils {
                       content = StrRes.rejectedByCaller;
                       break;
                     case 'timeout':
-                      content = StrRes.callTimeout;
+                      content = StrRes.unansweredCall;
                       break;
                     case 'networkError':
                       content = StrRes.networkAnomaly;