fix(webhook): retry logic

[wolf31o2]

Closes #334

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Summary by cubic

Adds retry with exponential backoff for webhook delivery to improve reliability and prevent lost events. Addresses #334 by handling transient failures and reporting exhausted retries.

• Bug Fixes

  • Retries failed webhook sends with exponential backoff and a max backoff cap.
  • Logs attempts and final failure; sends a non-blocking error to errorChan.

• New Features

  • Configurable retry via WithRetryConfig(maxRetries, initialBackoff, maxBackoff).
  • Defaults: 3 retries, 1s initial backoff, 30s max backoff, factor 2.0.

^{Written for commit 4a95a79. Summary will update on new commits.}

[cubic-dev-ai]

No issues found across 2 files