Defines tracer event types for tracking system interactions.

Tracer events are used to track system interactions for observability purposes. They are distinct from regular events which are used for agent communication.

All tracer events include:

• timestamp: Unix timestamp (seconds since epoch) when the event occurred
• correlation_id: UUID string copied from cause-to-effect for tracing events
• source: Module or component that generated the event

Each event type provides a printable_summary/1 function that returns a formatted string representation of the event for debugging and observability.