add package.json to initial agents dir

Author: charleslien

common/src/templates/initial-agents-dir/package.json

@@ -0,0 +1,6 @@
+{
+  "name": "codebuff-agents",
+  "version": "0.0.0",
+  "description": "This directory contains your custom Codebuff agents. Each agent is a TypeScript file that defines an AI agent with specific capabilities and behavior.",
+  "license": "Apache-2.0"
+}