Fix: show current-month renewals in collect payment wizard

The wizard only generated renewal invoices when next_billing_date had
already passed. Now it generates them for any billing date within the
current month, so participants can renew as soon as the month starts
rather than waiting for the exact billing day.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/Livewire/Receptionist/CollectPaymentWizard.php

@@ -188,7 +188,7 @@ private function generatePendingRenewals(): void
         $enrollments = Enrollment::where('participant_id', $this->selected_participant_id)
             ->where('status', EnrollmentStatus::Active)
             ->whereNotNull('next_billing_date')
-            ->where('next_billing_date', '<=', now()->toDateString())
+            ->where('next_billing_date', '<=', now()->endOfMonth()->toDateString())
             ->whereHas('program', function ($q) {
                 $q->whereIn('renewal_policy', [
                     RenewalPolicy::AutoRenew->value,