v2.16.1 — Card-picker live preview, drag-to-preview, editor entity-picker fix

Added

• Live preview in the card picker. Picking the Lightener Studio card from Home Assistant's Community card selector now renders a live preview of the curve editor instead of a blank tile, so you can see the card before adding it.
• Drag a point to preview one light. While editing a curve, dragging a single light's point now live-previews just that light in real time, easing to the dragged brightness as you drag.

Fixed

• The card editor's entity dropdown now lists only Lightener groups. Configuring a Lightener Studio card previously offered every light in the entity picker, so picking a normal light errored — the card can only target a Lightener group. The picker is now narrowed to Lightener groups. The in-card "Add light" picker for group members is unchanged; it still lists all lights, since members are ordinary lights.
• Dragging the floor point previews the dimmed level. Editing a curve's origin/floor point now previews the light at the dragged dim level instead of turning it off.