SidePanelLayout content is not rendered on open until a page repaint

[Flaurite]

Environment

Jmix version: 3.0.2

Bug Description

When a SidePanelLayout is opened, the components inside the side panel (e.g. TextField, ComboBox, Select) are not painted: the panel area
appears empty even though the components exist in the DOM and are correctly laid out. The content becomes visible only after the browser performs a full repaint - for example, zooming the page in or out.

Root cause is a Chromium paint-invalidation issue: slotted content projected into the panel's shadow subtree is not repainted when the panel becomes visible. Related to #5602.

Steps To Reproduce

1. Create a view with a SidePanelLayout and put input components (TextField, ComboBox, Select) into the side panel content.
2. Open the application and open the side panel.
3. Look at the side panel content.

Current Behavior

The side panel content is blank - no field borders, text, or controls are visible.

Expected Behavior

The side panel content is rendered immediately when the panel is opened, without requiring a page repaint.