Remove app/Space folder and extract model business logic into services

Relocate all 14 files from the catch-all app/Space namespace into proper
locations: data providers to Support/Formatters, installation utilities to
Services/Installation, PDF utils to Services/Pdf, module/update classes to
Services/Module and Services/Update, SiteApi trait to Traits, and helpers
to Support.

Extract ~1,400 lines of business logic from 8 fat models (Invoice, Payment,
Estimate, RecurringInvoice, Company, Customer, Expense, User) into 9 new
service classes with constructor injection. Controllers now depend on
services instead of calling static model methods. Shared item/tax creation
logic consolidated into DocumentItemService.

app/Http/Controllers/V1/Admin/Payment/SendPaymentController.php

@@ -5,11 +5,16 @@ namespace App\Http\Controllers\V1\Admin\Payment;
 use App\Http\Controllers\Controller;
 use App\Http\Requests\SendPaymentRequest;
 use App\Models\Payment;
+use App\Services\PaymentService;
 use Illuminate\Http\JsonResponse;
 use Illuminate\Http\Request;
 
 class SendPaymentController extends Controller
 {
+    public function __construct(
+        private readonly PaymentService $paymentService,
+    ) {}
+
     /**
      * Handle the incoming request.
      *
@@ -20,7 +25,7 @@ class SendPaymentController extends Controller
     {
         $this->authorize('send payment', $payment);
 
-        $response = $payment->send($request->all());
+        $response = $this->paymentService->send($payment, $request->all());
 
         return response()->json($response);
     }