feat: refactor role system to is_admin flag, add Badge component, fix native dialogs

- Separate admin identity from role: viewer|model + is_admin boolean flag
- DB migration 0001_is_admin: adds column, migrates former admin role users
- Update ACL helpers, auth session, GraphQL types and all resolvers
- Admin layout guard and header links check is_admin instead of role
- Admin users table: show Admin badge next to name, remove admin from role select
- Admin user edit page: is_admin checkbox toggle
- Install shadcn Badge component; use in admin users table
- Fix duplicate photo keys in adminGetUser resolver
- Replace confirm() in /me recordings with Dialog component

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/types/src/index.ts

@@ -21,7 +21,8 @@ export interface User {
   slug: string | null;
   description: string | null;
   tags: string[] | null;
-  role: "model" | "viewer" | "admin";
+  role: "model" | "viewer";
+  is_admin: boolean;
   /** UUID of the avatar file */
   avatar: string | null;
   /** UUID of the banner file */