`Drawer.Backdrop` loses layer stack variables after dragging content

### Description When i drag content, i expect that the variables don't disappear, but currently they disappear and `z-index: calc(100 + var(--layer-index))` calculation breaks. https://github.com/user-attachments/assets/073c361b-794d-4a09-bfbd-0cf47fe9a163 ### Link to Reproduction (or Detailed Explanation) https://stackblitz.com/edit/ivbcxkqr?file=src%2FApp.svelte&showSidebar=0 ### Steps to Reproduce 1. Click open. 2. Drag content. 3. Open backdrop in the devtools. 4. Notice there are no `--layer-index`, `--nested-layer-count` and `--z-index` variables. ### Ark UI Version 5.22.0 ### Framework - [ ] React - [ ] Solid - [ ] Vue - [x] Svelte ### Browser _No response_ ### Additional Information _No response_