feat(kcp): add signature URL to knowledge.yaml

Points to https://raw.githubusercontent.com/Cantara/java-modules-json2/master/knowledge.yaml.sig

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: totto

knowledge.yaml

@@ -21,6 +21,7 @@ signing:
   scheme: ed25519
   scope: this-manifest
   public_key: https://wiki.cantara.no/.well-known/kcp-signing-key.pub
+  signature: https://raw.githubusercontent.com/Cantara/java-modules-json2/master/knowledge.yaml.sig
 
 kcp_version: "0.14"
 project: java-modules-json2