The server was dropping the `data` field from hook-event POST requests,
so notifications always showed generic messages. Now forwards tool name,
command, question text, and reason to the frontend.
Notifications now show:
- permission_prompt: "Bash: docker push prod:latest"
- elicitation_dialog: "Merge PR #42 to main?"
- idle_prompt: custom message if provided
- stop: reason if provided
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>