fix(badges): display print timestamps in local browser time instead of UTC

The backend returns naive UTC datetime strings (no Z suffix). dayjs was treating
them as local time, so staff in ET saw UTC times. Added treat_as_utc param to
iso_datetime_formatter (default false, zero breakage to existing call sites) that
appends Z before parsing so dayjs converts to browser-local time on display.

Applied to all print timestamp call sites in badge list (first/last print visible
row + debug row) and to created_on/updated_on in the debug row.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/lib/ae_utils/ae_utils__datetime_format.ts

@@ -27,7 +27,11 @@ export const iso_datetime_formatter = function iso_datetime_formatter(
     named_format: string = 'datetime_iso_no_seconds', // date_iso, datetime_iso_no_seconds
     // Pass true/false to resolve to the correct 12h or 24h variant automatically.
     // null (default) leaves named_format unchanged — all existing call sites unaffected.
-    use_12h: boolean | null = null
+    use_12h: boolean | null = null,
+    // When true, treats a naive datetime string (no Z / offset) as UTC so dayjs
+    // converts it to local browser time on display. Use for timestamps stored as
+    // UTC in the DB but returned without a timezone indicator.
+    treat_as_utc: boolean = false
 ) {
     // console.log('*** iso_datetime_formatter() ***');
 
@@ -74,6 +78,12 @@ export const iso_datetime_formatter = function iso_datetime_formatter(
         raw_datetime = new Date(); // Get the current datetime if one was not passed.
     }
 
+    // Append 'Z' to naive UTC strings so dayjs converts to local browser time.
+    // Guards against double-appending if the backend ever adds timezone info.
+    if (treat_as_utc && typeof raw_datetime === 'string' && !raw_datetime.match(/Z$|[+-]\d{2}:?\d{2}$/)) {
+        raw_datetime = raw_datetime + 'Z';
+    }
+
     if (use_12h !== null) {
         named_format = use_12h
             ? (TO_12H[named_format] ?? named_format)