Sort invoices list by payment date first, then creation date

Shows most recently paid invoices at the top so the user sees
the latest actual money collected, not just the latest generated.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/Livewire/Invoices/InvoiceList.php

@@ -87,6 +87,7 @@ public function render()
                 });
             })
             ->when($this->status, fn ($q) => $q->where('status', $this->status))
+            ->orderByDesc('paid_at')
             ->orderByDesc('created_at');
 
         $this->applyRoleScope($query);