Improve braket

[peng1999]

Current implementation gives inconsistent height of angles and vertical bars in braket. Until typst/typst#641 have merged, I propose to use following workaround to make the formula more pleasant.

#let braket(bra, ket) = style(styles => {
  let height = measure($ bra ket $, styles).height;
  let phantom = box(height: height, width: 0pt, inset: 0pt, stroke: none);
  $ lr(angle.l bra lr(|phantom#h(0pt)) ket angle.r) $
})

Result:

[Leedehai]

谢啦