fix(editor): centerize iframe modal in mobile (#13073)

Close
[BS-3160](https://linear.app/affine-design/issue/BS-3160/新的-embed-输入的-sheet-没有弹起来)

#### PR Dependency Tree


* **PR #13073** 👈

This tree was auto-generated by
[Charcoal](https://github.com/danerwilliams/charcoal)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

* **Bug Fixes**
* Improved popup positioning and responsiveness when using virtual
keyboards, ensuring popups remain visible and correctly placed above the
keyboard.
* Standardized how popups and overlays are created and referenced
throughout the app, reducing inconsistencies and potential display
issues.
* Enhanced stability of date picker, AI panels, and slash menu popovers
by refining how their elements are managed and updated.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

blocksuite/affine/data-view/src/property-presets/date/cell-renderer.ts

@@ -78,7 +78,7 @@ export class DateCell extends BaseCellRenderer<number, number> {
         },
       });
     } else {
-      const root = createLitPortal({
+      const { portal } = createLitPortal({
         abortController,
         closeOnClickAway: true,
         computePosition: {
@@ -107,7 +107,7 @@ export class DateCell extends BaseCellRenderer<number, number> {
       //       for now the slide-layout-modal's z-index is `1001`
       //       the z-index of popover should be higher than it
       // root.style.zIndex = 'var(--affine-z-index-popover)';
-      root.style.zIndex = '1002';
+      portal.style.zIndex = '1002';
     }
   };