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/Database/Migrations/2026-08-16-000200_RemoveAdditionalDuplicateCalendarConfigurationKeys.php

@@ -0,0 +1,30 @@
+<?php
+
+namespace App\Database\Migrations;
+
+use CodeIgniter\Database\Migration;
+
+class RemoveAdditionalDuplicateCalendarConfigurationKeys extends Migration
+{
+    private const DUPLICATE_KEYS = [
+        'end_of_registration',
+        'last_school_day',
+        'year_end_date',
+    ];
+
+    public function up(): void
+    {
+        if (! $this->db->tableExists('configuration')) {
+            return;
+        }
+
+        $this->db->table('configuration')
+            ->whereIn('config_key', self::DUPLICATE_KEYS)
+            ->delete();
+    }
+
+    public function down(): void
+    {
+        // Obsolete duplicate keys should not be recreated.
+    }
+}