feat(keys): the conversation list walks with j/k; the cheat sheet names keys in the reader's language

E11 S5 — the HU/EN sweep and the keyboard-only pass over every module.

- The keyboard cheat sheet printed "Space" and "Menu" on a Hungarian sheet: a keycap that carries a
  WORD (not a legend every layout prints alike, like Esc, Ctrl or Enter) is now named by the caller in
  the reader's language (`formatChord(chord, words)`, `keys.cap.*`: Szóköz / Menü).
- The Plex player's ⌫/Esc line said "Stop & back to feed", but the player goes back to wherever it
  was opened from (Home, a Plex page): "Stop & go back" / "Leállítás és vissza".
- Messages: the conversation list is a keyboard list (NavGrid + navItemAttrs, the name button is the
  open element; the pop-out button keeps its own Enter). D1 covers every list whose rows open one
  thing; this one was missed in S4. Notification cards have no single open action and stay out, like
  the download queue.

Sweep, measured: every static `t("…")` key used in the source exists in both languages (the only
misses are template prefixes); the HU values equal to EN are proper nouns and loanwords (Admin, Plex,
Trakt, Shorts). Palette in Hungarian: "téma" makes "Téma: Midnight" the active row ahead of the channel
"Topik - mindig témában", live region "7 találat".

Keyboard-only pass in Chrome, Hungarian UI — 1024×768: every `g` chord lands on its module, `j` rings
the first item (solid 2px accent) on Home, Feed, Channels, Playlists, Plex and Downloads, `s` focuses
the search on Feed, Channels, Playlists and Plex, no page scrolls sideways. 3440×1440: `j` → → ↓
walks Home, Feed (8 columns: 0 → 1 → 9), Channels, Playlists, Plex and Downloads, no sideways scroll.
The help sheet lists every line translated; inside the Plex player "Szóköz / K" and "⌫ / Esc
Leállítás és vissza". Messages: a real `j` rings the row, Enter opens the thread.

frontend/src/lib/keymap.test.ts

@@ -213,11 +213,19 @@ describe("helpLines", () => {
 });
 
 describe("formatChord", () => {
+  const words = { Space: "Szóköz", ContextMenu: "Menü" };
+
   it("renders glyphs and upper-cases the letter", () => {
-    expect(formatChord("ArrowLeft")).toBe("←");
-    expect(formatChord("Backspace")).toBe("⌫");
-    expect(formatChord("Shift+ArrowRight")).toBe("⇧ →");
-    expect(formatChord("k")).toBe("K");
-    expect(formatChord("Space")).toBe("Space");
+    expect(formatChord("ArrowLeft", words)).toBe("←");
+    expect(formatChord("Backspace", words)).toBe("⌫");
+    expect(formatChord("Shift+ArrowRight", words)).toBe("⇧ →");
+    expect(formatChord("k", words)).toBe("K");
+  });
+
+  // A key whose cap carries a word is named in the reader's language: the Hungarian sheet said "Space".
+  it("names a word key in the caller's language", () => {
+    expect(formatChord("Space", words)).toBe("Szóköz");
+    expect(formatChord("ContextMenu", words)).toBe("Menü");
+    expect(formatChord("Shift+F10", words)).toBe("⇧ F10");
   });
 });