Add discovery registry review flow

docs/registry-api.md

@@ -29,6 +29,38 @@ GET  /repositories/{repo_slug}/snapshots/diff
 Snapshot ingestion accepts a `FabricGraphExport` under `graph` plus `commit`
 and optional `generated_at`.
 
+## Discovery Snapshots
+
+```text
+POST /repositories/{repo_slug}/discovery-snapshots
+GET  /repositories/{repo_slug}/discovery-snapshots
+GET  /repositories/{repo_slug}/discovery-snapshots/latest
+GET  /repositories/{repo_slug}/discovery-snapshots/diff
+GET  /repositories/{repo_slug}/discovery-snapshots/{snapshot_id}
+POST /repositories/{repo_slug}/discovery-snapshots/{snapshot_id}/accept
+```
+
+Discovery ingestion accepts a `FabricDiscoverySnapshot`. Snapshots are stored by
+repo, commit, and scan profile for dry-run review. Discovery diffs include
+candidate additions, removals, changes, confidence changes, reconciliation
+conflicts, and scoped retirements.
+
+Acceptance projects only explicitly accepted discovery candidates into a normal
+`FabricGraphExport` snapshot. Existing graph nodes are preserved, so repo-owned
+declarations are not overwritten by discovery output. Projected nodes carry
+discovery provenance, review state, confidence, and source anchors in their
+attributes; graph explorer exports surface that metadata.
+
+CLI helpers:
+
+```bash
+railiance-fabric registry ingest-discovery discovery.json \
+  --repo-slug railiance-fabric
+
+railiance-fabric registry accept-discovery railiance-fabric 12 \
+  --accepted-key discovery:railiance-fabric:service-declaration:example
+```
+
 ## Graph Queries
 
 ```text