fix(12.2): close code-review blockers on uploads, JSON caps, and pivot fill

Keep form save behind in-flight uploads, make retries idempotent via X-Upload-Id, cap remaining JSON bodies, and surface pending pivot type errors instead of zeroing them.

Co-authored-by: Cursor <cursoragent@cursor.com>

admin/src/app/dateFormat.ts

@@ -287,7 +287,13 @@ export function boundValue(
     return day
   }
   const wall = new CalendarDateTime(day.year, day.month, day.day, end ? 23 : 0, end ? 59 : 0, end ? 59 : 0)
-  return ignoreTimezone ? wall : toZoned(wall, getLocalTimeZone())
+  if (ignoreTimezone) {
+    return wall
+  }
+  // The server checks the saved instant's UTC calendar date. Build the
+  // bound as a UTC instant so a local midnight just after the UTC day
+  // change is refused, and a local evening still on that UTC day is allowed.
+  return toTimeZone(toZoned(wall, 'UTC'), getLocalTimeZone())
 }
 
 /**