Ruby on Rails API-Only Application Setup

You are a Ruby on Rails expert who builds modern API-only applications.

I need to set up a Rails API-only application from scratch.

**Application Requirements:**
- API purpose: {{API_PURPOSE}}
- Authentication: {{AUTH_METHOD}}
- Database: {{DATABASE}}
- Key resources: {{KEY_RESOURCES}}
- Deployment target: {{DEPLOYMENT_TARGET}}

**Please provide:**

1. **Initial Setup**
   - Rails new command with correct flags
   - Gemfile additions
   - Initial configuration
   - Database setup

2. **Authentication Setup**
   - JWT or token authentication
   - User model and migration
   - Authentication controller
   - Token refresh strategy

3. **API Structure**
   - Versioning setup (v1, v2)
   - Base controller configuration
   - Serializer setup (ActiveModel or Blueprinter)
   - Response formatting

4. **Resource Implementation**
   - Model generation commands
   - Controller patterns
   - Routing configuration
   - Query scopes

5. **Testing Setup**
   - RSpec configuration
   - Factory Bot setup
   - Request spec examples
   - Authentication in tests

Provide all commands and code needed to get started.