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/layout/main_layout.php

@@ -233,7 +233,7 @@ html, body { overflow-x: hidden; }
             } catch (\Throwable $e) {
                 $sy = (string)($cfg->getConfig('school_year') ?? '');
             }
-            $sem = (string)($cfg->getConfig('semester') ?? '');
+            $sem = (string)(getSemester() ?? '');
             $uid = (int)(session()->get('user_id') ?? 0);
             if ($uid) {
                 $classOptions = $tcModel->getClassAssignmentsByUserId($uid, $sy, $sem);