fix: compute Date.now() per call instead of at module load

The fallback enrollment date was frozen when the module first loaded.
If the app stayed open across midnight, courses with null lastEnrolled
would get a stale timestamp.

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

Author: arbrandes

src/utils/dataTransformers.ts

@@ -2,18 +2,20 @@ import { FilterKeys, ListPageSize, SortKeys } from '@src/data/constants/app';
 import StrictDict from './StrictDict';
 
 const cardId = (val) => `card-${val}`;
-const today = Date.now();
 
-const transformCourseData = (courses) => courses.reduce(
+const transformCourseData = (courses) => {
+  const now = Date.now();
+  return courses.reduce(
   (obj, curr, index) => {
     const out = { ...curr, cardId: cardId(index) };
     if (out.enrollment?.lastEnrolled === null) {
-      out.enrollment.lastEnrolled = today;
+      out.enrollment.lastEnrolled = now;
     }
     return { ...obj, [cardId(index)]: out };
   },
   {},
 );
+};
 
 const getTransformedCourseDataObject = (courses) => transformCourseData(courses);