The hook commands now read stdin JSON from Claude Code (contains tool_name,
tool_input, etc.) and forward it as the data field to the API. This enables
richer notifications showing actual context (e.g., "Bash: docker push prod").
Previously the curl commands only sent event type and session ID, losing
all hook context data.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>