Add Request Timeout Support

[AryanSharma48]

A request may hang indefinitely even when retries are configured.

Add configurable timeout support to automatically abort requests that exceed a specified duration.

Example

createResilientFetch({
  timeoutMs: 5000
});

Acceptance Criteria

• Support configurable timeout values
• Abort requests after timeout
• Add unit tests
• Update documentation
• Preserve current behavior when timeout is not configured