Snapshot fails when box is idle

[enesakar]

Description

When a box is in an idle state, calling snapshot operations fails. Snapshots should work regardless of whether the box is currently active or idle.

Steps to reproduce

1. Create a box and set it up with files/dependencies
2. Wait for the box to become idle (or let it idle naturally)
3. Attempt to take a snapshot of the idle box

Expected behavior

Snapshot should succeed even when the box is idle — the box state should be capturable at any time.

Actual behavior

Snapshot operation fails on idle boxes.

Context

We run long-lived boxes (@upstash/box SDK) that go idle between scheduled agent runs. We need to snapshot them for backup/restore purposes, but can only do so while they're actively running.