Feature request: Hook event for permission prompts

When Claude stops for a permission prompt (tool approval), the Stop hook doesn't fire. There's no way to get notified that Claude is waiting for user input in this case.

Request: Add a hook event (e.g. PermissionPrompt) that fires when Claude is waiting for the user to approve/deny a tool call.

Use case: Playing a notification sound so the user knows Claude needs attention, rather than sitting idle unknowingly. Currently the Stop hook covers end-of-turn stops, but permission prompts are a mid-turn pause that goes unnoticed.