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/Policies/OrganisationPolicy.php

@@ -0,0 +1,40 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Policies;
+
+use App\Models\Organisation;
+use App\Models\User;
+
+final class OrganisationPolicy
+{
+    public function viewAny(User $user): bool
+    {
+        // All authenticated users can list their organisations
+        return true;
+    }
+
+    public function view(User $user, Organisation $organisation): bool
+    {
+        return $user->hasRole('super_admin')
+            || $organisation->users()->where('user_id', $user->id)->exists();
+    }
+
+    public function create(User $user): bool
+    {
+        return $user->hasRole('super_admin');
+    }
+
+    public function update(User $user, Organisation $organisation): bool
+    {
+        if ($user->hasRole('super_admin')) {
+            return true;
+        }
+
+        return $organisation->users()
+            ->where('user_id', $user->id)
+            ->wherePivot('role', 'org_admin')
+            ->exists();
+    }
+}