Without a mouse the channel banner was invisible: opening a channel focused the
first video card, which scrolled the header (a grid item) off-screen. The header
is now pinned above the grid and never scrolls away. The banner is its backdrop,
darkened to black at the bottom; the avatar sits beside the title with a
"by <owner> on <platform>" byline, the subscriber/video/created stats, and the
description flowing into the black beneath (a long one grows the header down
instead of being clipped). A Subscribe button sits on the banner, reachable with
UP from the first card, wired to the same follow/unfollow as the player.
AGENTS.md: subscribing is in scope (already on the player, now the channel page
too), so drop it from the excluded list.
Jeena
21d8290f1d