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/Settings/MailConfigurationController.php

@@ -6,7 +6,7 @@ use App\Http\Controllers\Controller;
 use App\Http\Requests\MailEnvironmentRequest;
 use App\Mail\TestMail;
 use App\Models\Setting;
-use App\Space\EnvironmentManager;
+use App\Services\Installation\EnvironmentManager;
 use Illuminate\Auth\Access\AuthorizationException;
 use Illuminate\Http\JsonResponse;
 use Illuminate\Http\Request;