v0.52.0

### Added

- **Node health in Homer.** With `[hep]` shipping to a collector, each node now sends its
  own health as HEP `Log` (0x64) chunks keyed by `node:<[node].id>`, so Homer shows a
  per-node timeline: `node_started` at boot, `node_ready` / `node_not_ready` /
  `node_draining` as `/ready` and the drain flag change, a `node_status` heartbeat every
  `[hep].node_status_interval_secs` (new; default 60, `0` = off, below 5 fails the load),
  and `node_stopping` at teardown, queued before the HEP worker drains. Each line carries
  version, ready, draining, active calls, registrations and uptime — the
  `GET /admin/v1/status` snapshot plus `/ready`, read from the same sources so they cannot
  disagree. New counter `siphon_ai_hep_node_events_total{event}`. Format in HEP.md's new
  *Node health Log chunks* section.

---

**Artifacts**

- Static musl binaries for `x86_64` and `aarch64` (`.tar.gz`).
- Debian packages (`.deb`) for `amd64` and `arm64` — `apt install ./siphon-ai_*_amd64.deb`.
- `SHA256SUMS` — verify with `sha256sum -c SHA256SUMS`.
- `*-sbom.cdx.json` — CycloneDX SBOM.
- `SHA256SUMS.cosign.bundle` — cosign keyless signature over the checksums.
- Container: `ghcr.io/thevoiceguy/siphon-ai:v0.52.0` (multi-arch, cosign-signed).

Verify the checksums signature:
```
cosign verify-blob --bundle SHA256SUMS.cosign.bundle \
  --certificate-oidc-issuer https://token.actions.githubusercontent.com \
  --certificate-identity-regexp 'release.yml@' SHA256SUMS
```