feat: Add Lifecycle Event Hooks for Telemetry (Tracking Issue)

[AryanSharma48]

Expose lifecycle hooks to allow consumers to observe retry and circuit breaker activity.

Request & Tracing Lifecycle

• onRequestStart
• onAttemptStart
• onRetry [feat] Add onRetry and onCircuitStateChange lifecycle hooks #35
• onSuccess feat: add onSuccess and onFailure lifecycle hooks for telemetry #58
• onFailure feat: add onSuccess and onFailure lifecycle hooks for telemetry #58

Resilience, Fallbacks & Edge Cases

• onFallback
• onTimeout
• onDeduplicate

Circuit Breaker Observability

• onCircuitStateChange [feat] Add onRetry and onCircuitStateChange lifecycle hooks #35
• onCircuitOpen
• onCircuitClose
• onCircuitHalfOpen
• onCircuitReject

Acceptance Criteria

• Design hook interface
• Implement lifecycle events
• Add documentation
• Add examples
• Add tests