* **New Features**
* Asynchronous certificate prefetch that races live issuance with periodic on-disk cache checks to surface certificates faster.
* Centralized recording and notification when certificates become available.
* New on-disk certificate reading and validation to allow immediate use of cached certs.
* **Bug Fixes & Performance**
* Optimized retrieval by polling disk while fetching in background to reduce latency.
* Added cancellation and timeout handling to fail stalled certificate operations reliably.
* **New Features**
* Access logs now include bytes_upload and bytes_download (API and schemas updated, fields required).
* Certificate issuance duration is now recorded as a metric.
* **Refactor**
* Metrics switched from Prometheus client to OpenTelemetry-backed meters; health endpoint now exposes OpenMetrics via OTLP exporter.
* **Tests**
* Metric tests updated to use OpenTelemetry Prometheus exporter and MeterProvider.
