Start ecosystem registry service

docs/ecosystem-registry-service.md

@@ -184,6 +184,34 @@ stable, the backing store can be replaced or expanded.
 7. CycloneDX SBOM attachment for library/package inventory.
 8. CloudEvents-style registry events once mutation endpoints exist.
 
+## First Service Slice
+
+The initial implementation is deliberately dependency-light:
+
+- `railiance_fabric.registry` owns SQLite persistence, snapshot validation, and
+  graph query helpers.
+- `railiance_fabric.server` exposes a stdlib HTTP service.
+- `railiance-fabric-registry` starts the service.
+
+The first endpoint set is:
+
+```text
+GET  /health
+POST /repositories
+GET  /repositories
+GET  /repositories/{repo_slug}
+POST /repositories/{repo_slug}/snapshots
+GET  /repositories/{repo_slug}/snapshots/latest
+GET  /graph/nodes
+GET  /graph/nodes/{graph_id}
+GET  /graph/providers?capability_type=runtime-secrets
+GET  /graph/consumers?target=railiance-platform.openbao.kv-v2
+GET  /graph/unresolved
+GET  /graph/blast-radius?interface_id=openbao-kv-v2-mount
+GET  /graph/dependency-path?service_id=flex-auth.api
+GET  /exports/state-hub
+```
+
 ## Open Design Questions
 
 - Should the registry pull repos itself, or should repos/agents push validated