Event-Driven Job Queue v1.1

Adds observability and runtime metrics:

• /metrics endpoint
• queue depth tracking
• execution & queue latency metrics
• success/failure/retry/DLQ counters
• performance documentation

Focus: production visibility and operability

v1.0 – Crash-resilient single-node job queue

Initial stable release of a single-node, at-least-once background
job processing system with crash recovery, bounded retries,
and graceful shutdown semantics.