# Task 02 — Metrics / Health Surface

**Goal:** expose runtime stats (uptime, WAL lag, open handles) without requiring full observability stack.

## Deliverables
- Optional HTTP endpoint (disabled by default) serving `/metrics` (Prometheus text) and `/healthz` (JSON).
- Builder flag `enable_metrics(addr)` + `with_metrics(false)` toggle for tests.
- Metrics counters tagged with `process`, `partition_id`, `build_hash` for future distributed rollouts.

## Acceptance Criteria
- Endpoint can run on the same Tokio runtime as host service (returns `Future` implementor).
- Minimal deps (hyper/tiny_http) to keep embeddable footprint light.
- Integration test hits `/metrics` and asserts counters increment when WAL appends.
