Record repository UI status in the scanner and tolerate older jsonschema.

Adds the repo-ui-metadata extractor (ui_status yes/candidate/not_detected
plus ui_evidence), falls back to the legacy validator when jsonschema does
not accept a referencing registry, and covers unknown edge endpoints in the
graph explorer.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Assistant: claude-code
Assistant-Model: opus
Assistant-Process: 7458@bnt-lap001
Assistant-Session: 62534cdf-8348-48a7-9c0d-46e0f74c8eae

railiance_fabric/schema_validation.py

@@ -39,10 +39,17 @@ def draft202012_validator(schema_path: Path) -> jsonschema.Draft202012Validator:
     registry = schema_registry(schema_path.parent)
     if registry is None:
         return _legacy_validator(schema_path, schema)
-    return jsonschema.Draft202012Validator(
-        schema,
-        registry=registry,
-    )
+    try:
+        return jsonschema.Draft202012Validator(
+            schema,
+            registry=registry,
+        )
+    except TypeError as exc:
+        # jsonschema < 4.17 does not accept referencing.Registry. Keep the
+        # same schema set usable on older operator workstations.
+        if "unexpected keyword argument 'registry'" not in str(exc):
+            raise
+        return _legacy_validator(schema_path, schema)
 
 
 def _legacy_validator(