Add retry capability with exponential backoff for HTTP requests.
- Implement withRetry utility with configurable retry logic
- Exponential backoff: 1s, 2s, 4s, 8s (max)
- Maximum 3 retries by default
- Retry on network errors (ECONNREFUSED, ETIMEDOUT, etc.)
- Retry on 5xx server errors and 429 rate limit
- Do NOT retry on 4xx client errors
- Integrate with connection service for HTTP requests
Fixes#293
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>