Adopt SummerCMS v0.1.1 admin features

Datepickers on native time.Time / lagoon.Date fields, file uploads on
materials, readings and class sessions managed from the course form
(course_id made nullable).

controllers/api/params.go

@@ -99,11 +99,11 @@ func dayStart(in map[string]any, name string) (time.Time, bool) {
 	if s == "" {
 		return time.Time{}, false
 	}
-	t, err := models.ParseDate(s)
+	d, err := models.ParseDate(s)
 	if err != nil {
 		return time.Time{}, false
 	}
-	return t, true
+	return d.Time(models.Location), true
 }
 
 // today returns midnight of now's calendar day in Europe/Warsaw.