Desktop: Persist computer-use app approvals across a session's lifetime, not just until exit

Problem

Per the docs, computer-use app approvals last for the current session, and the lock releases only when the session exits -- there's no setting to change that. Combined with sessions auto-archiving on their own (#68972, #59449, #60043, #67811), this means an approval you gave five minutes ago can vanish through no action of your own, and you re-approve from zero.

There's also no way to pre-authorize an app for computer use ahead of time. Every session starts cold, even for the same app you approved a dozen times already.

What I'm asking for

• A way to persist "always allow computer use for [app]" across sessions, scoped per-app the way file/bash permissions already support an allowlist
• At minimum, computer-use approvals should survive an auto-archive event on the same underlying session -- losing the approval should require the user actually exiting, not an idle timer firing in the background