- Switch popover from position:absolute to position:fixed to avoid
scroll-offset math and simplify viewport clamping.
- Add max-height + overflow-y:auto so the popover scrolls internally
instead of overflowing the viewport.
- Remove the reposition call after picker opens — this was causing
the popover to flash and jump when the picker changed its height.
- Improve edge clamping: if neither above nor below fits, clamp to
viewport bottom rather than flipping unpredictably.
- Remove the CSS arrow (::before) which was mispositioned when the
popover appeared above the badge or near edges.
Co-authored-by: Cursor <cursoragent@cursor.com>