case 4739 - browser that can't name its time zone: its own offset instead of New York

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/api/locale.js

@@ -37,7 +37,7 @@ export default {
   // Get users default time zone
   // first check if overriden in useroptions
   // if not then use browsers own setting
-  // if that is empty then final default of "America/New_York"
+  // if the browser can't name its time zone then its current offset from UTC
   //https://www.iana.org/time-zones
   //https://en.wikipedia.org/wiki/List_of_tz_database_time_zones
   getResolvedTimeZoneName() {
@@ -49,7 +49,14 @@ export default {
       if (!window.$gz.util.stringIsNullOrEmpty(tz)) {
         return tz;
       } else {
-        return "America/New_York";
+        //case 4739: e.g. a new Windows time zone the browser doesn't know yet; this used to be "America/New_York"
+        //a fixed offset zone in whole hours, the only kind every browser and luxon accept by name
+        //(Etc/GMT signs are reversed: UTC-7 is Etc/GMT+7, which is what getTimezoneOffset returns, 420 minutes)
+        const hours = Math.round(new Date().getTimezoneOffset() / 60);
+        if (hours == 0) {
+          return "Etc/GMT";
+        }
+        return `Etc/GMT${hours > 0 ? "+" : "-"}${Math.abs(hours)}`;
       }
     }
   },