Route user comments through CEO agent via issue.comment.created event

Add event handler that intercepts user comments on issues and wakes the
CEO agent (instead of only the assigned agent). The CEO reads the comment,
checks for attachments, and routes to the appropriate agent.

- Add issue.comment.created event subscription
- Add agents.read, agents.invoke, issue.comments.read capabilities
- CEO receives comment body + issue context in the invoke prompt

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

plugin.json

@@ -13,6 +13,9 @@
     "issues.create",
     "issues.update",
     "issue.comments.create",
+    "issue.comments.read",
+    "agents.read",
+    "agents.invoke",
     "agent.tools.register",
     "http.outbound",
     "plugin.state.read",