Option to compress numpy array in `hovertemplate` `customdata` for `px.imshow`

Our application enables the generation of multiplexed images, where image regions show multiple "markers" in a tissue sample to demonstrate spatial patterns of marker co-occurrence.

We enable users to toggle a custom hovertemplate that shows the underlying raw array values for each marker before they are converted to RGB:

However, this becomes noticeably slower as the number of markers grows linearly; we pass the customdata template as a stacked numpy array paired with custom hovertext.

An option to compress this template array would help in increasing the speed and effectiveness of using customdata for our hovertemplate

该 issue 未指出任何文件或测试；请先定位 px.imshow 以及 customdata 与 hovertemplate 的处理方式，然后确定现有的 NumPy-array 路径。要视为完成，需要定义压缩选项、保留 hover 值，并就性能证据达成一致，而该 issue 目前没有明确其中任何一项。