A notice's word under the pointer is lit, in its band and the grid; mark_hover is gone

Open point 6 of docs/render-pipeline.md: notice words are Look and Exec
targets, so the hover affordance headers have is back on notices, painted
once in the notice's layer and joined into the grid from it. Deleted:
Surface.mark_hover, Cell.hover and render's per-frame reset of it, none of
which had been set since stage 5 (macOS loses its glass hover rect; its
build is ignored for now). Snapshot goldens unchanged.

Shared files touched: macos.zig (the hover bit's removal). Not touched:
pardes.zig, Messages.zig, mouse.zig, gui.zig, detached/*.

0 files changed, 0 insertions, 0 deletions