fix(ui): a focused, disabled FocusSafeButton no longer lights up on hover

A FocusSafeButton that holds the focus is disabled by aria-disabled, not the native attribute, so
every hover gated on `:disabled` / `enabled:` alone still fired on it — the glass lift, the primary /
danger / warn dim, and eight `enabled:hover:` chains (saved views, the player's list buttons, the
undo toolbar). Measured on localdev: the Pager's Next, focused at the last page, now keeps its resting
border and shadow under the pointer. The CSS selectors and the chains also exclude
`[aria-disabled="true"]`, and a lint rule refuses a bare `enabled:hover:` from now on.

frontend/src/components/PlaylistLimitsHint.tsx

@@ -21,7 +21,12 @@ export default function PlaylistLimitsHint() {
     offset: 8,
   });
   return (
-    <div className="mt-2 flex items-center gap-1.5 border-t border-border/60 px-1 pt-2 text-2xs text-muted">
+    // The panel is placed off the whole row, not the "Why?" button: off the button it opened
+    // over the right third of the rail and covered the lists (measured on localdev).
+    <div
+      ref={pop.refs.setPositionReference}
+      className="mt-2 flex items-center gap-1.5 border-t border-border/60 px-1 pt-2 text-2xs text-muted"
+    >
       <Info className="h-3.5 w-3.5 shrink-0" aria-hidden="true" />
       <span>{t("playlists.limits.hint")}</span>
       <button