Add configurable notification delay (notify only after user inactivity)

Feature Request

Problem

Currently, Claude Code sends a terminal bell notification immediately every time it finishes responding. When a user is actively working at their computer and responding quickly, this creates a stream of unnecessary notifications that can be disruptive.

Proposed Solution

Add a configurable notification delay setting, e.g.:

{
  "notificationDelay": 60
}

Behavior: After Claude Code finishes responding, wait N seconds before sending the terminal bell. If the user starts typing/responds within that window, skip the notification entirely.

This way:

• Users who are actively engaged in the conversation won't be bothered by constant notifications
• Users who step away will still get notified after the delay period
• Setting to 0 preserves current behavior (immediate notification)

Use Case

As a developer using Claude Code via SSH (e.g., Termius), I often work side-by-side with Claude. When I'm actively at the keyboard, I don't need a notification for every response — I can see it. But if I step away to check something else, I'd like to be notified after ~60 seconds of inactivity that Claude is waiting for my input.

Additional Context

This could be a setting in ~/.claude/settings.json or a CLI flag like --notify-delay 60.