fix(select): blank panel with virtualScroll + lazy in dialog (

[khaledbaghdadii]

Fixes #19401

Problem

When p-select is configured with [virtualScroll]="true" and [lazy]="true" inside a p-dialog
with appendTo="body", the dropdown panel opens blank. Items only appear after an additional user
interaction (click, keypress).

Root Cause

p-motion's afterRenderEffect uses await nextFrame() (double requestAnimationFrame), which
causes execution to escape NgZone. The onAfterEnter animation callback fires outside NgZone,
so the scroller's entire initialization chain (init → setTimeout → calculateOptions → onLazyLoad)
runs outside the zone. Angular never detects the subsequent item updates, leaving the panel blank.

Fix

Add an onOverlayAfterEnter handler that re-enters NgZone via zone.run() before triggering
cd.detectChanges(). This ensures all downstream async operations (setTimeout, lazy load events,
data fetches) are intercepted by zone and trigger change detection when they resolve.

onOverlayAfterEnter(event: any) {
    if (this.virtualScroll) {
        this.zone.run(() => {
            this.cd.detectChanges();
        });
    }
}

[domvanrob]

I've got the same issue with the overlay in my TreeSelect component. Running this manually after the onShow output fixes it.