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/app/src/@core/enums.ts

@@ -0,0 +1,21 @@
+export const Skins = {
+  Default: 'default',
+  Bordered: 'bordered',
+} as const
+
+export const Theme = {
+  Light: 'light',
+  Dark: 'dark',
+  System: 'system',
+} as const
+
+export const Layout = {
+  Vertical: 'vertical',
+  Horizontal: 'horizontal',
+  Collapsed: 'collapsed',
+} as const
+
+export const Direction = {
+  Ltr: 'ltr',
+  Rtl: 'rtl',
+} as const