refactor(support): group Bouncer, Media, Setup files into subdirs

Finishes the Support/ consolidation pass: the three remaining root-level files get grouped into purpose-named subdirs, matching the shape the Pdf/, Hashids/, Update/, and Module/ subdirs took in the earlier sweep.

- BouncerDefaultScope → Support/Bouncer/ (Bouncer-specific authorization scope)

- CustomPathGenerator → Support/Media/ (Spatie MediaLibrary path generator — media config references it from config/media-library.php)

- InstallWizardAuth → Support/Setup/ (folded into the existing Setup/ subdir alongside EnvironmentManager, FilePermissionChecker, InstallUtils, RequirementsChecker — it's install-wizard-flow state)

4 consumer files updated (AppServiceProvider, LoginController, UseInstallWizardTokenAuth middleware, config/media-library.php). app/Support/ root is now completely empty of standalone PHP files except helpers.php.

app/Support/Setup/InstallWizardAuth.php

@@ -0,0 +1,21 @@
+<?php
+
+namespace App\Support\Setup;
+
+use Illuminate\Http\Request;
+
+class InstallWizardAuth
+{
+    public const HEADER = 'X-Install-Wizard';
+
+    public const HEADER_VALUE = '1';
+
+    public const TOKEN_NAME = 'installation-wizard';
+
+    public const TOKEN_ABILITY = 'installation:wizard';
+
+    public static function isRequest(Request $request): bool
+    {
+        return $request->headers->get(self::HEADER) === self::HEADER_VALUE;
+    }
+}