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/Libraries/InvoiceLedgerService.php

@@ -103,8 +103,10 @@ class InvoiceLedgerService
             $totalAmountCents = $tuitionCents + $eventCents + $additionalCents;
         }
 
-        $rawBalanceCents = $totalAmountCents - $discountCents - $paidCents + $refundPaidCents;
+        $netChargeCents = $totalAmountCents - $discountCents;
+        $rawBalanceCents = $netChargeCents - $paidCents - $refundPaidCents;
         $balanceCents = max(0, $rawBalanceCents);
+        $customerCreditCents = max(0, $paidCents - $refundPaidCents - $netChargeCents);
 
         if ($balanceCents === 0) {
             $status = FinancialStatus::INVOICE_PAID;
@@ -120,14 +122,14 @@ class InvoiceLedgerService
             'discount_eligible_base_cents' => $discountBaseCents,
             'requested_discount_cents' => $discountRawCents,
             'applied_discount_cents' => $discountCents,
-            'net_charge_cents' => $totalAmountCents - $discountCents,
+            'net_charge_cents' => $netChargeCents,
             'totalAmountCents' => $totalAmountCents,
             'discountCents' => $discountCents,
             'paidCents' => $paidCents,
             'completedRefundCents' => $refundPaidCents,
             'rawBalanceCents' => $rawBalanceCents,
             'balanceDueCents' => $balanceCents,
-            'customerCreditCents' => max(0, -$rawBalanceCents),
+            'customerCreditCents' => $customerCreditCents,
             'tuition_total' => $this->fromCents($tuitionCents),
             'event_total' => $this->fromCents($eventCents),
             'additional_total' => $this->fromCents($additionalCents),
@@ -136,7 +138,7 @@ class InvoiceLedgerService
             'paid_amount' => $this->fromCents($paidCents),
             'refund_paid_total' => $this->fromCents($refundPaidCents),
             'total_amount' => $this->fromCents($totalAmountCents),
-            'customer_credit' => $this->fromCents(max(0, -$rawBalanceCents)),
+            'customer_credit' => $this->fromCents($customerCreditCents),
             'balance' => $this->fromCents($balanceCents),
             'status' => $status,
             'has_discount' => $discountCents > 0 ? 1 : 0,