Extension: let the Twin ‘What-if’ preview be applied as an approve-only plan – currently it writes nothing, so a useful simulation dead-ends

WHAT: The Twin ‘WHAT IF – PREVIEW ONLY’ panel lets you move intake/exhaust/light sliders and toggle appliances to see the scene respond, but ‘Nothing here is written to a device’. WHY: a good simulation that can’t become an action dead-ends; operators will want to say ‘yes, do that’. HOW: add an ‘apply as approve-only plan’ path from a what-if state -> the same gradual/approve-only mechanism the Light energy suggestions already use (‘Start gradual…’), so the operator can turn a simulated setpoint/duty into a staged, confirmed change. Keep preview-only as the default. Extends the Twin + existing approve-only plan machinery. Found live 8.2.0.