CLI: expose and update "last used" time for items

The Proton Pass apps (desktop, browser, mobile) all track and show when each item was last used, which makes it easy to spot stale credentials and to sort by what you actually use. The CLI is the only client that ignores this: it never shows a "last used" value and never updates it, even though the API already returns the field.

I'd love the CLI to match the apps here:

1. Show "last used" in item list / item view JSON output, alongside the created/modified times that are already there.
2. Update it when an item is actually used from the CLI — item view, item totp, and especially run / inject, which are how secrets get consumed in scripts and CI.
3. Optionally, let item list --sort-by last-used order by it.

Use case: credential hygiene. With this I could audit a vault for credentials nobody uses anymore, and confirm that the secrets my automation depends on are still alive. Right now a login read every hour by a cron job looks completely unused from the CLI's point of view.

This would bring the CLI in line with the rest of the Proton Pass ecosystem for power users who live in the terminal.

I've put together a working reference implementation if it helps: https://github.com/bsramin/pass-cli/pull/1