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

apps/admin/src/plugins/casl/ability.ts

@@ -2,8 +2,7 @@ import { createMongoAbility } from '@casl/ability'
 
 export type Actions = 'create' | 'read' | 'update' | 'delete' | 'manage'
 
-// ex: Post, Comment, User, etc. We haven't used any of these in our demo though.
-export type Subjects = 'Post' | 'Comment' | 'all'
+export type Subjects = 'Post' | 'Comment' | 'User' | 'Event' | 'Organisation' | 'all'
 
 export interface Rule { action: Actions; subject: Subjects }