claudetool: remove knowledge base, focus on about sketch

We should have a more general kb.
Meanwhile, this is important and standalone.
Make it all clearer and sharper.
diff --git a/llm/llm.go b/llm/llm.go
index 9331961..3de6b7f 100644
--- a/llm/llm.go
+++ b/llm/llm.go
@@ -27,6 +27,10 @@
 	return json.RawMessage(bytes)
 }
 
+func EmptySchema() json.RawMessage {
+	return MustSchema(`{"type": "object", "properties": {}}`)
+}
+
 type Request struct {
 	Messages   []Message
 	ToolChoice *ToolChoice