fix: revert SetUserAuth/SetPassword to direct property syntax

Now that the SDK uses string instead of *string for AddAuthArgs,
gomobile exposes userAuth and password as direct string properties
that Swift can assign to with dot syntax.

Author: Ryanmello07

app/network/Main/Account/Settings/AddAuthSheet.swift

@@ -114,8 +114,8 @@ struct AddAuthSheet: View {
             let args = SdkAddAuthArgs()
 
             if selectedMethod == "email" {
-                args.SetUserAuth(email)
-                args.SetPassword(password)
+                args.userAuth = email
+                args.password = password
             }
             // seedphrase is generated server-side, no args needed