feat: implement user authentication and task management with JWT support

[soltanoff]

Task: #197 + #200 + #291

This pull request introduces a new multi-domain architecture with support for user authentication (JWT-based), task management, and translation, and exposes these domains across all supported transports (REST, gRPC, AMQP RPC, NATS RPC). It adds new gRPC service definitions for authentication and task management, updates documentation in three languages, and enhances configuration for JWT. There are also minor improvements to the developer workflow and environment setup.

Major new features and architecture:

• Introduced three domains—User Authentication (registration, login, JWT-based authorization), Task Management (CRUD with status transitions), and Translation (with history)—all available via REST, gRPC, AMQP RPC, and NATS RPC. [1] [2] [3]

gRPC service definitions:

• Added auth.proto and generated auth_grpc.pb.go defining AuthService with Register, Login, and GetProfile RPCs. [1] [2]
• Added task.proto defining TaskService with CRUD and status transition RPCs for tasks.

Configuration and environment:

• Added JWT configuration (JWT_SECRET, JWT_TOKEN_EXPIRY) to .env.example, docker-compose.yml, and the Go config package to support JWT-based authentication. [1] [2] [3] [4] [5]

Documentation updates:

• Updated README.md, README_CN.md, and README_RU.md to describe the new domains and their availability across all transports. [1] [2] [3]
• Added links to the new proto files in all three READMEs for gRPC service discovery. [1] [2] [3]

Developer workflow improvements:

• Ensured integration test containers are cleaned up after running with make compose-up-integration-test.
• Added dependency installation to the pre-commit target in the Makefile.