Add config to disable idle/awaiting-input reminder notification separately from completion notifications

Problem

Claude Code fires a notification (terminal bell or system notification) ~60 seconds after a response completes if no new user input has been received. This happens even when the user was actively in the window when the response finished — they read it and switched windows, and then get notified anyway.

There is currently no way to disable this idle reminder without also disabling completion notifications entirely. The only notification setting available disables all notifications.

Expected behavior

Either:

1. A separate config option to disable the idle/awaiting-input reminder independently of completion notifications, or
2. The idle reminder should not fire if the window was focused when the response completed (i.e., the user demonstrably saw it)

Current behavior

• Task completes, user reads it while window is active
• User switches to another window
• ~60 seconds later, notification fires as a "hey, respond to me" nudge
• No config exists to suppress just this behavior

Request

Add a granular config (e.g. idleReminderEnabled: false) so users can keep completion notifications without the nagging reminder.