Set the velcro overlay position:absolute from CSS to stop the first-frame jump

The hover overlay is positioned by velcro (floating-ui), but it only became
`position: absolute` inside the offset middleware — which runs *after*
floating-ui has already measured the rects on the first computePosition. So
the first frame was measured against the wrong containing block and the whole
overlay (the teal type-label tab, the select chip, the menu, the outline)
painted ~60px off, then snapped into place one frame later.

floating-ui requires the floating element to already be absolutely positioned
when it first measures. Declare `position: absolute` in the overlay's CSS so
it is in effect before velcro's first measurement; the middleware still sets
it too, harmlessly. Confirmed via frame-by-frame capture that the overlay's
own top/left was the thing jumping (526->466 between frame 0 and 1), so fixing
it here fixes every piece of chrome that rides the overlay.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: lukemelia

packages/host/app/components/operator-mode/operator-mode-overlays.gts

@@ -218,6 +218,14 @@ export default class OperatorModeOverlays extends Overlays {
     </AdornContext>
     <style scoped>
       .actions-overlay {
+        /* Establish `position: absolute` from CSS, before velcro's first
+           computePosition runs. floating-ui requires the floating element to
+           already be absolutely positioned when it first measures; the offset
+           middleware also sets this, but that runs *after* the initial
+           measurement, so without it here the overlay (and everything riding
+           it — the type-label tab, the select chip, the menu) lands ~1 frame
+           off and visibly jumps into place on first hover. */
+        position: absolute;
         pointer-events: none;
         /* Allow the type-label tab and selection chip to extend outside the
            overlay's bounding box without being clipped. */

packages/host/app/components/operator-mode/overlays.gts

@@ -95,6 +95,13 @@ export default class Overlays extends Component<OverlaySignature> {
     {{/each}}
     <style scoped>
       .base-overlay {
+        /* Establish `position: absolute` from CSS, before velcro's first
+           computePosition runs. floating-ui requires the floating element to
+           already be absolutely positioned when it first measures; the offset
+           middleware also sets this, but that runs *after* the initial
+           measurement, so without it here the overlay lands ~1 frame off and
+           visibly jumps into place on first appearance. */
+        position: absolute;
         width: 100%;
         height: 100%;
         pointer-events: none;