feat(ecosystem): hub-core library lane for three-repo stack (HUB-WP-0003)

Add slugify_or_default for core-hub parity, bump to 0.2.0, document ecosystem
position in INTENT/SCOPE/README, wire capability relations to state-hub and
core-hub, and extend utils tests. Part of CUST-WP-0057 consolidation.

registry/capabilities/capability.infotech.hub-core-library.md

@@ -68,8 +68,11 @@ availability:
   - library import
 relations:
   depends_on: []
-  supports: []
-  related_to: []
+  supports:
+    - capability.infotech.core-hub
+  related_to:
+    - capability.infotech.core-hub
+    - capability.statehub.workstream-coordinate
 evidence:
   documentation:
   - README.md

registry/indexes/capabilities.yaml

@@ -1,5 +1,5 @@
 version: 1
-updated: '2026-07-06'
+updated: '2026-07-09'
 domain: inter_hub
 capabilities:
 - id: capability.infotech.hub-core-library