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/Controllers/View/FlagController.php

@@ -367,7 +367,7 @@ class FlagController extends Controller
         $userId = session()->get('user_id');
 
         // Get the semester and school year from configuration
-        $semester = $configModel->getConfig('semester');
+        $semester = getSemester();
         $schoolYear = $configModel->getConfig('school_year');
 
         // Set the current system date and time for flag_datetime