Fix semester context, attendance rosters, and billing workflows

- load global semester helpers consistently and use date-based semester defaults
- fix grading and daily attendance duplicate student/section rows
- keep attendance violations scoped to the current semester by default
- update invoice, refund, discount, payment, and financial aid flows
- add configuration cleanup migrations for duplicate calendar/semester keys
- refresh parent registration/report-card and print request handling
- update related models, services, views, cron notes, and test coverage

app/Views/teacher/teacher_navbar.php

@@ -71,7 +71,7 @@
                         } catch (\Throwable $e) {
                             $sy = $configModel->getConfig('school_year');
                         }
-                        $sem = $configModel->getConfig('semester');
+                        $sem = getSemester();
                         $classOptions = $teacherClassModel->getClassAssignmentsByUserId((int)$userId, (string)$sy, (string)$sem);
                     }
                 ?>