feat(hooks): run boot.md on gateway startup

docs/reference/templates/BOOT.md

@@ -0,0 +1,9 @@
+---
+summary: "Workspace template for BOOT.md"
+read_when:
+  - Adding a BOOT.md checklist
+---
+# BOOT.md
+
+Add short, explicit instructions for what Clawdbot should do on startup (enable `hooks.internal.enabled`).
+If the task sends a message, use the message tool and then reply with NO_REPLY.