fix(keys): epic-end review round 1 — Back, menus and dialogs keep the focus where it belongs

Deep-review of E11 (19 raised, 14 confirmed; 2 refuted, 3 latent test-hardening notes dropped).

- Back from a sub-view (a Plex show page, a Messages thread) restores the item it was opened from
  even when focus was still inside the view: the first attempt now waits one task, past the
  sub-view's own popstate listener (measured in Chrome: it left focus on <body>).
- The restore listener is installed at load, so the first Back after a reload finds it; a push
  cancels a restore still waiting for the last landing's lists.
- Navigating over an overlay asks it again, a render apart, while its entry stays: the Plex
  player peels one panel per Back step, so Shift+W over info + stats closed one panel and dropped
  the navigation.
- j/k: a native <button> item keeps its own Tab stop; landing twice on the same item no longer
  leaks its tabindex; after the focused item is removed (a hidden card) the next j goes on from
  its slot when that slot is on screen.
- An abandoned `g` no longer swallows a modifier chord (g, then Mod+K opened the browser search).
- A hover card above a dialog no longer switches its Tab trap off (player, Modal, wizard,
  Lightbox): new layerStack `anyBlockingLayerAbove`.
- "Manage views…" closes its menu before opening the dialog, through a shared `closeThenAct`
  that ActionMenu now uses too.
- Copy: the EN welcome says "Feed"; the EN unreachable reason no longer claims a change;
  stale comments about PlayerModal's scroll lock and dialog contract.

frontend/src/components/OnboardingWizard.tsx

@@ -125,8 +125,9 @@ export default function OnboardingWizard({ me, onClose }: { me: Me; onClose: ()
   useDialogChrome(panelRef, rootRef);
   useEffect(() => {
     const onKey = (e: KeyboardEvent) => {
-      // Only while nothing is above us: an error dialog opened from inside the wizard owns the Tab.
-      if (e.key !== "Tab" || !layer.isTopmost()) return;
+      // Only while nothing that owns the keyboard is above us: an error dialog opened from inside the
+      // wizard owns the Tab, a hover card under the pointer does not.
+      if (e.key !== "Tab" || layer.blockingAbove()) return;
       const panel = panelRef.current;
       // The SAME three arguments `ui/Modal` passes, for the same two reasons — and this call had
       // neither of them (round 6, on the commit that extracted the helper so the two shells could