Refactor: cache IsReadAndConfirm() result in variable

Store envelope.IsReadAndConfirm() in isReadAndConfirm variable to avoid redundant calls and improve code readability when setting ViewData["Title"]. No change to logic or behavior.

EnvelopeGenerator.Web/Views/Envelope/ShowEnvelope.cshtml

@@ -25,9 +25,11 @@
     if (ViewData["IsReadOnly"] is bool isReadOnly_bool)
         isReadOnly = isReadOnly_bool;
 
+    var isReadAndConfirm = envelope.IsReadAndConfirm();
+
     ViewData["Title"] = isReadOnly
         ? _localizer.ViewDoc()
-        : envelope.IsReadAndConfirm()
+        : isReadAndConfirm
             ? _localizer.ConfirmDoc()
             : _localizer.SignDoc();
 }