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/Organisation.php

@@ -0,0 +1,50 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Concerns\HasUlids;
+use Illuminate\Database\Eloquent\Factories\HasFactory;
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsToMany;
+use Illuminate\Database\Eloquent\Relations\HasMany;
+use Illuminate\Database\Eloquent\SoftDeletes;
+
+final class Organisation extends Model
+{
+    use HasFactory;
+    use HasUlids;
+    use SoftDeletes;
+
+    protected $fillable = [
+        'name',
+        'slug',
+        'billing_status',
+        'settings',
+    ];
+
+    protected function casts(): array
+    {
+        return [
+            'settings' => 'array',
+        ];
+    }
+
+    public function users(): BelongsToMany
+    {
+        return $this->belongsToMany(User::class, 'organisation_user')
+            ->withPivot('role')
+            ->withTimestamps();
+    }
+
+    public function events(): HasMany
+    {
+        return $this->hasMany(Event::class);
+    }
+
+    public function invitations(): HasMany
+    {
+        return $this->hasMany(UserInvitation::class);
+    }
+}