Consolidate Pdf controllers: 6 -> 1 DocumentPdfController

Merge InvoicePdfController, EstimatePdfController, PaymentPdfController
into DocumentPdfController with invoice(), estimate(), payment() methods.

Delete DownloadInvoicePdfController and DownloadPaymentPdfController
(dead code — not mapped in any routes).

Move DownloadReceiptController logic to ExpensesController::downloadReceipt()
(expense receipts, not PDF documents).

app/Http/Controllers/Pdf/DocumentPdfController.php

@@ -0,0 +1,46 @@
+<?php
+
+namespace App\Http\Controllers\Pdf;
+
+use App\Http\Controllers\Controller;
+use App\Models\Estimate;
+use App\Models\Invoice;
+use App\Models\Payment;
+use App\Services\EstimateService;
+use App\Services\InvoiceService;
+use Illuminate\Http\Request;
+
+class DocumentPdfController extends Controller
+{
+    public function __construct(
+        private readonly InvoiceService $invoiceService,
+        private readonly EstimateService $estimateService,
+    ) {}
+
+    public function invoice(Request $request, Invoice $invoice)
+    {
+        if ($request->has('preview')) {
+            return $this->invoiceService->getPdfData($invoice);
+        }
+
+        return $invoice->getGeneratedPDFOrStream('invoice');
+    }
+
+    public function estimate(Request $request, Estimate $estimate)
+    {
+        if ($request->has('preview')) {
+            return $this->estimateService->getPdfData($estimate);
+        }
+
+        return $estimate->getGeneratedPDFOrStream('estimate');
+    }
+
+    public function payment(Request $request, Payment $payment)
+    {
+        if ($request->has('preview')) {
+            return view('app.pdf.payment.payment');
+        }
+
+        return $payment->getGeneratedPDFOrStream('payment');
+    }
+}