feat(auth): add bootstrap token flow for initial admin creation

- Introduced `BootstrapService` to handle admin creation when no admins exist.
- Added `/auth/bootstrap-admin` endpoint to consume bootstrap tokens.
- Updated `RbacRepository` to support counting admins and assigning roles.
- Included unit tests for `BootstrapService` to ensure token behavior and admin assignment.

backend/src/auth/auth.module.ts

@@ -3,6 +3,7 @@ import { SessionsModule } from "../sessions/sessions.module";
 import { UsersModule } from "../users/users.module";
 import { AuthController } from "./auth.controller";
 import { AuthService } from "./auth.service";
+import { BootstrapService } from "./bootstrap.service";
 import { AuthGuard } from "./guards/auth.guard";
 import { OptionalAuthGuard } from "./guards/optional-auth.guard";
 import { RolesGuard } from "./guards/roles.guard";
@@ -15,6 +16,7 @@ import { RbacRepository } from "./repositories/rbac.repository";
 	providers: [
 		AuthService,
 		RbacService,
+		BootstrapService,
 		RbacRepository,
 		AuthGuard,
 		OptionalAuthGuard,