feat(claude): add MaxRetries configuration option

[pintonunes]

Summary

Add support for configuring retry behavior through the MaxRetries option in all Claude model implementations (Direct API, Vertex AI, and AWS Bedrock).

Changes

• Added MaxRetries *int field to the Config struct
• Updated NewChatModel to apply option.WithMaxRetries() for all three implementations:
  • Direct Anthropic API
  • Google Vertex AI
  • AWS Bedrock
• Added comprehensive documentation explaining:
  • Default behavior: 2 retries if not specified
  • Set to 0 to disable retries
  • Set to positive integer for custom retry count

Testing

• All existing tests pass
• Build successful for all implementations

Usage Example

maxRetries := 3
config := &claude.Config{
    APIKey:     "your-api-key",
    Model:      "claude-3-5-sonnet-20241022",
    MaxTokens:  2000,
    MaxRetries: &maxRetries, // Configure retry behavior
}
model, _ := claude.NewChatModel(ctx, config)