Add Frontdesk-style Devices registry for POS hardware.

Register tills, customer displays, kitchen screens, printers, scanners,
and tablets per branch. Customer displays share the branch display token
and mark online when the public screen polls; stale devices go offline
on a schedule.

app/Http/Controllers/Public/CustomerDisplayController.php

@@ -6,6 +6,7 @@ use App\Http\Controllers\Controller;
 use App\Models\PosCustomerDisplay;
 use App\Models\PosSale;
 use App\Services\Pos\CustomerDisplayService;
+use App\Services\Pos\DeviceService;
 use App\Services\Pos\ReceiptEmailService;
 use Illuminate\Http\JsonResponse;
 use Illuminate\Http\Request;
@@ -18,11 +19,13 @@ class CustomerDisplayController extends Controller
     public function __construct(
         private CustomerDisplayService $displays,
         private ReceiptEmailService $receiptEmail,
+        private DeviceService $devices,
     ) {}
 
     public function show(string $token): View
     {
         $display = $this->find($token);
+        $this->devices->touchByToken($token);
 
         return view('pos.customer-display', [
             'display' => $display,
@@ -36,6 +39,7 @@ class CustomerDisplayController extends Controller
     public function state(string $token): JsonResponse
     {
         $display = $this->find($token);
+        $this->devices->touchByToken($token);
 
         return response()->json($this->displays->publicState($display));
     }