Reworks the channel detail per UAT: instead of the banner scrolling away
and a sticky sub-header (which felt odd to scroll and needed an opaque bar
that clashed with the design even at rest), the ENTIRE chrome — banner,
identity, tabs, toolbar — is fixed and only the video grid scrolls.
Mechanism: ChannelPage wraps its whole chrome in <PageToolbar> so it
portals into the shell's fixed band (like the feed toolbar); the
channelScoped Feed portals its toolbar into a slot at the bottom of that
chrome. No sticky, no opaque bar — the chrome is transparent over the page
bg because nothing scrolls under it (the band sits above the scroller).
E2E updated: the channel chrome (title + toolbar) stays at a fixed
viewport position while the grid scrolls. Suite 15/15, tsc clean.
peter
ec807c8b31