Root cause of the upload-modal file-picker regression: the modal's
React Spring enter spring transitions
`transform: scale(0.95) translateY(-10px)` → `scale(1) translateY(0)`.
With PageScene's heavier render loop, the spring takes long enough
that a click on a small deep child (the file uploader's "Upload a
file" `<u>` link, ~10px tall) lands its mousedown on the `<u>` and
its mouseup on a different element after the modal shifted. WebView2
strictly requires same-target mousedown/mouseup to synthesize
`click`, so no `click` fires, the library's native
`addEventListener("click", u)` on the label never runs, and
`inputRef.current.click()` is never called.
Animate opacity only on enter/leave. Same fade visual, no element
movement under the cursor.
Also strip the now-unused TEMP click tracer from PageEditor.tsx.
Tanish Manku
4167bf22ce