refactor(modules): migrate asset registry from app/Services to invoiceshelf/modules package

The vestigial App\Services\Module\Module static class — with its unused
\$scripts / \$styles / \$settings registries — never had any of its helpers
wired up. The new InvoiceShelf\Modules\Registry shipped from the
invoiceshelf/modules package supersedes it cleanly: same static-array surface
(\$menu, \$settings, \$scripts, \$styles), but lives outside the host app so
third-party modules can depend on it without importing v3-app internals.

Three consumers in the host app are migrated to the new namespace:

- ScriptController and StyleController (the HTTP endpoints that serve
  module-registered JS/CSS assets at /modules/scripts/{name} and
  /modules/styles/{name}) now look up paths via Registry::scriptFor() and
  Registry::styleFor() instead of Arr::get(ModuleFacade::all*(), \$name).
  Also tightens type hints — Request import + Response return type.

- resources/views/app.blade.php iterates Registry::allStyles() /
  Registry::allScripts() to inject module-supplied <link>/<script> tags into
  the main layout. Same Akaunting-style asset injection mechanism, just
  reading from the new namespace.

Both Module and ModuleFacade are deleted — they had no remaining callers
after this migration.

app/Http/Controllers/Modules/ScriptController.php

@@ -3,27 +3,27 @@
 namespace App\Http\Controllers\Modules;
 
 use App\Http\Controllers\Controller;
-use App\Services\Module\ModuleFacade;
 use DateTime;
+use Illuminate\Http\Request;
 use Illuminate\Http\Response;
-use Illuminate\Support\Arr;
-use Request;
+use InvoiceShelf\Modules\Registry as ModuleRegistry;
 use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
 
 class ScriptController extends Controller
 {
     /**
-     * Serve the requested script.
+     * Serve the requested module-registered script.
      *
-     * @return Response
+     * Modules call \InvoiceShelf\Modules\Registry::registerScript($name, $path)
+     * from their ServiceProvider::boot() to inject custom JS into the host app.
      *
      * @throws NotFoundHttpException
      */
-    public function __invoke(Request $request, string $script)
+    public function __invoke(Request $request, string $script): Response
     {
-        $path = Arr::get(ModuleFacade::allScripts(), $script);
+        $path = ModuleRegistry::scriptFor($script);
 
-        abort_if(is_null($path), 404);
+        abort_if($path === null, 404);
 
         return response(
             file_get_contents($path),
@@ -31,6 +31,6 @@ class ScriptController extends Controller
             [
                 'Content-Type' => 'application/javascript',
             ]
-        )->setLastModified(DateTime::createFromFormat('U', filemtime($path)));
+        )->setLastModified(DateTime::createFromFormat('U', (string) filemtime($path)));
     }
 }