The available channels table rendered inside its own
"card overflow-hidden" wrapper instead of the ".table-wrapper" element
that TablePageLayout's scroll chain expects. The outer
.table-scroll-container is overflow-hidden, so when the channel list
grew taller than the viewport the content was simply clipped with no
scrollbar. The extra card wrapper also drew a double border inside the
layout's own card chrome.
Mount the table on .table-wrapper like every other table page so it
receives overflow-y-auto from the layout, and add a source-convention
regression test in the style of TablePageLayout.spec.ts.
Fixes#4555
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
