Add Custom API Server Endpoint Support

[waxiangzi]

Summary

This PR adds support for configurable API server endpoints through the OPS0_API_BASE_URL environment variable, enabling users to connect to custom Claude-compatible API services while maintaining full backward compatibility.

Changes

Core Implementation

• definitions.go: Added APIBaseURL field to ClaudeConfig struct
• llms.go: Updated callClaude() to use configurable endpoint with fallback to default
• main.go: Added OPS0_API_BASE_URL environment variable reading
• action.go: Updated interactive mode configuration
• ansible.go: Updated Ansible AI integration configuration

Key Features

1. Configurable Endpoint: Set custom API server via OPS0_API_BASE_URL
2. Backward Compatible: Defaults to https://api.anthropic.com when not set
3. Consistent Naming: Follows existing OPS0_* environment variable convention
4. Cross-Platform: Works on all supported platforms (macOS, Linux, Windows)

Usage Examples

Default Behavior (Unchanged)

export ANTHROPIC_API_KEY=sk-xxx
ops0 -m "show docker containers" -ai

Custom API Endpoint

export ANTHROPIC_API_KEY=sk-xxx
export OPS0_API_BASE_URL=https://api.custom-provider.com
export OPS0_AI_MODEL=custom-model-name
ops0 -m "show docker containers" -ai

Testing

✅ Compilation: All platforms compile successfully

• macOS ARM64
• Linux x86_64
• Linux ARM64
• Windows x86_64

✅ Functionality: Tested with both default and custom endpoints

• Default Anthropic API works unchanged
• Custom API endpoint correctly used
• Chinese language support maintained
• All existing features preserved

✅ Environment Variables: Complete configuration support

export ANTHROPIC_API_KEY=sk-xxx
export OPS0_API_BASE_URL=https://openrouter.ai/api
export OPS0_AI_MODEL=anthropic/claude-3.5-sonnet

Benefits

• Enterprise Ready: Supports corporate proxies and custom gateways
• Provider Flexibility: Works with any Claude-compatible API service
• Regional Support: Enables use of regional endpoints for compliance/latency
• Development Friendly: Useful for testing with local API servers

Backward Compatibility

This change is 100% backward compatible:

• Existing users see no change in behavior
• No breaking changes to existing environment variables
• Default API endpoint remains https://api.anthropic.com

Closes #9