Add retry mechanism for API calls

[0xperp]

Closes #3

This PR implements a robust retry mechanism for API calls to improve reliability when interacting with external services like the Anthropic API. It includes:

• A withRetry utility function that wraps async operations with configurable retry logic
• Exponential backoff for retries to reduce load during outages
• Configurable retry policies (max attempts, delays, retry conditions)
• Unit tests to verify the retry mechanism works correctly

Usage Example

// In anthropic.ts
import { withRetry } from './utils/retry';

// Create a retry-enabled version of the API call
const callAnthropicWithRetry = withRetry(
  client.logAndCreateChatCompletion.bind(client),
  {
    maxRetries: 3,
    initialDelay: 1000,
    backoffFactor: 2,
    isRetriable: (error) => {
      // Retry on rate limit errors or network issues
      return error.status === 429 || error.code === 'ECONNRESET';
    }
  }
);

// Use the retry-enabled function instead of the regular API call
const result = await callAnthropicWithRetry(params);

This enhancement will make the bot more resilient to temporary network issues, rate limits, and other transient API errors.