feat(tables): a glyph pager with first/last, and tablet-width columns step aside

The pager is four named arrows round the page box (first, previous,
next, last). A table hides a tabletHidden column below 64rem of its own
width, as narrowHidden does below 42rem, through one shared helper that
also hides the column's <col>. The Channels table drops Prio, About and
Length there: at 1024 the channel name had 60 px.

frontend/src/components/channelColumns.tsx

@@ -88,6 +88,8 @@ export function buildChannelColumns(deps: ChannelColumnDeps): Column<ManagedChan
       header: t("channels.cols.priority"),
       align: "center",
       width: "5.5rem",
+      // Off on a tablet-wide table, with About and Length: the row's "…" menu sets the priority too.
+      tabletHidden: true,
       sortable: true,
       hideInCard: true,
       sortValue: (c) => c.priority,
@@ -127,6 +129,7 @@ export function buildChannelColumns(deps: ChannelColumnDeps): Column<ManagedChan
       key: "about",
       header: t("channels.cols.about"),
       hideInCard: true,
+      tabletHidden: true,
       // The other FLUID column — AboutCell already truncates to its cell.
       render: (c) => <AboutCell text={c.description} channelId={c.id} />,
     },
@@ -157,6 +160,7 @@ export function buildChannelColumns(deps: ChannelColumnDeps): Column<ManagedChan
       align: "right",
       nowrap: true,
       width: "4.5rem",
+      tabletHidden: true,
       sortable: true,
       sortValue: (c) => c.total_duration_seconds,
       render: (c) => (