Fix flaky this-week/next-week grouping tests around the evening boundary

Both fixtures anchored their "this week" event at a hardcoded 18:00 on the
last day of the current week -- fine any other day, but once the suite runs
past 18:00 on that day itself, the anchor is already in the past and the
view's own start__gte=now filter correctly excludes it, failing the test
for a reason that has nothing to do with the grouping logic being tested.
Falls back to "a few minutes from now" (still always this week) whenever
the fixed anchor would already be behind now.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

mobile/tests.py

@@ -3143,7 +3143,13 @@ class CoachScheduleViewTests(TestCase):
 
     def test_events_are_grouped_into_this_week_next_week_and_month_dividers(self):
         _this_week_start, this_week_end = week_bounds(timezone.localdate())
-        this_week_event = Event.objects.create(club=self.club, title="This week practice", kind=Event.EventKind.TRAINING, start=timezone.make_aware(datetime.datetime.combine(this_week_end, datetime.time(18, 0))))
+        this_week_event_start = timezone.make_aware(datetime.datetime.combine(this_week_end, datetime.time(18, 0)))
+        if this_week_event_start <= timezone.now():
+            # See management.tests's own identical fallback on the same fixture
+            # shape -- the fixed 18:00 anchor is only "this week" if it's still
+            # ahead of now.
+            this_week_event_start = timezone.now() + datetime.timedelta(minutes=5)
+        this_week_event = Event.objects.create(club=self.club, title="This week practice", kind=Event.EventKind.TRAINING, start=this_week_event_start)
         this_week_event.teams.add(self.team)
         far_future = Event.objects.create(club=self.club, title="Far future practice", kind=Event.EventKind.TRAINING, start=timezone.now() + datetime.timedelta(days=60))
         far_future.teams.add(self.team)