chore(schema): add role support for constrained_by and governed_by

Roles can now be sources for constrained_by and governed_by
relationships. This enables expressing that a role is constrained by
invariants or governed by policies.

Resolves issue #25

Author: Mearman

src/endpoint-types.ts

@@ -98,6 +98,7 @@ export const RELATIONSHIP_ENDPOINT_TYPES: Record<
 			"decision",
 			"change",
 			"invariant",
+			"role",
 		],
 		to: ["invariant", "principle", "policy", "protocol", "concept"],
 	},
@@ -208,6 +209,7 @@ export const RELATIONSHIP_ENDPOINT_TYPES: Record<
 			"change",
 			"policy",
 			"artefact",
+			"role",
 		],
 		to: ["policy", "protocol", "role", "principle", "invariant", "concept"],
 	},