refactor: align codebase with EventCrew domain and trim legacy band stack

- Update API: events, users, policies, routes, resources, migrations
- Remove deprecated models/resources (customers, setlists, invitations, etc.)
- Refresh admin app and docs; remove apps/band

Made-with: Cursor

api/app/Models/Scopes/OrganisationScope.php

@@ -0,0 +1,21 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Models\Scopes;
+
+use Illuminate\Database\Eloquent\Builder;
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Scope;
+
+final class OrganisationScope implements Scope
+{
+    public function __construct(
+        private readonly string $organisationId,
+    ) {}
+
+    public function apply(Builder $builder, Model $model): void
+    {
+        $builder->where($model->getTable() . '.organisation_id', $this->organisationId);
+    }
+}