feat(billing): renewals, coupons, VAT numbering, billing cycles and invoice payment tracking

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

app/Http/Controllers/Api/Client/InvoiceLookupController.php

@@ -0,0 +1,40 @@
+<?php
+
+namespace App\Http\Controllers\Api\Client;
+
+use App\Http\Controllers\Controller;
+use App\Http\Requests\Api\Client\InvoiceLookupRequest;
+use App\Services\InvoicePdfService;
+use App\Support\InvoiceLookup;
+use Illuminate\Http\JsonResponse;
+use Illuminate\Http\Response;
+
+class InvoiceLookupController extends Controller
+{
+    private const NOT_FOUND = 'Không tìm thấy hóa đơn. Vui lòng kiểm tra lại số hóa đơn và mã tra cứu.';
+
+    public function show(InvoiceLookupRequest $request): JsonResponse
+    {
+        $invoice = InvoiceLookup::find($request->validated('invoice_number'), $request->validated('lookup_code'));
+
+        if (!$invoice) {
+            return response()->json(['error' => true, 'message' => self::NOT_FOUND], 404);
+        }
+
+        return response()->json(['error' => false, 'data' => InvoiceLookup::payload($invoice)]);
+    }
+
+    public function pdf(InvoiceLookupRequest $request, InvoicePdfService $pdfService): Response|JsonResponse
+    {
+        $invoice = InvoiceLookup::find($request->validated('invoice_number'), $request->validated('lookup_code'));
+
+        if (!$invoice) {
+            return response()->json(['error' => true, 'message' => self::NOT_FOUND], 404);
+        }
+
+        return response($pdfService->generate($invoice), 200, [
+            'Content-Type' => 'application/pdf',
+            'Content-Disposition' => 'attachment; filename="' . $pdfService->generateFileName($invoice) . '"',
+        ]);
+    }
+}