visualizer: explore replacing chrome devtools extension with in-page UI

[mreinstein]

chrome manifest v3 sucks. Rather than refactor the existing chrome plugin to work with v3 it might be better to expect a URL parameter like ?debug=true and when present, render some in-page html UI for showing the ECS panel.

besides the benefit of boycotting Chrome's extension changes it also would enable these devtool to run in other browsers, and with a simpler architecture.

[mreinstein]

if pursued this would invalidate #30 and #14