docs: the review classifier's try-out service, its key and its subject

- review-classifier.md: claude runs spawn through hive-claude directly
  with no tools and no session (hive-runtime holds only TurnStop); the
  answer's fields, the 500-character reason cap and what a failure does;
  how the try-out page reaches the classifier; the settled parts of the
  open list (API key path, try-out subject, --tools "" on claude).
  The banner stays.
- services.md: a Review classifier section with the two operator steps.
- secrets.md, credentials.md: the classifier's leaf and the key row.
- network.md: the container's row. CLAUDE.md: the crate.

docs/swarm/services.md

@@ -232,3 +232,24 @@ publishes to the secret store, which it reads under its own `ci-runner` leaf.
 On a host without the store, that leaf is the one file to copy. Registration,
 the container and the threat model are in
 [`../scheduler/ci.md`](../scheduler/ci.md).
+
+### Review classifier
+
+The review classifier's try-out service, in a `swarm-review-classifier`
+container on the host that sets `deploy.review-classifier.enable`. It doesn't
+derive from `allSwarmServices`: every run spends money on an Anthropic API
+key, so running one is a decision of its own.
+
+Two steps turn it on:
+
+1. Write the key in the secret store's UI at
+   `secret/swarm/services/review-classifier/anthropic-api-key`, field
+   `api_key`. The service reads it on every run, so writing or removing it
+   takes effect on the next run, with no restart.
+2. Set `services.hyperhive.deploy.review-classifier.enable = true` on a host.
+
+It needs neither the forge nor a hive on its host. It reaches the queue and the
+secret store by name, under its own `review-classifier` leaf. On a host
+without the store, that leaf is the one file to copy, as for the CI runner.
+The swarm UI's try-out page drives it through swarm-controller; what a run is
+and what it costs are in [`review-classifier.md`](review-classifier.md).