Design a complete gRPC API for {{application_domain}} using {{language}} and {{api_style}} with Auth0 integration. Write in a {{tone}} tone for backend engineers. Include: API design principles (naming, versioning, pagination, rate limiting), resource definitions with CRUD RPCs and protobuf schemas, authentication and authorization with Auth0 and RBAC, error handling using gRPC error model, advanced features (webhooks, batch ops, file uploads, real-time endpoints), documentation specification, and performance considerations. Every RPC must include a concrete protobuf message example. Keep under 1800 words. Skip any section if information is unknown. Paste any relevant background information after these instructions before running.