feat(e24): reach the Home surface — the landing toggle, a palette command, Shift+W

S4's reachability half. Home already led the nav order; what was missing was every
way IN other than the rail.

- Settings → Appearance → Startup: "Start on Home", the documented escape hatch for
  the landing override. Deliberately still localStorage and not a server pref —
  `loadInitialPage` answers before /api/me lands, and a landing module decided after
  the first paint is a visible jump. Its two stored values are now ONE exported
  constant, so the writer and the boot-time reader cannot drift on a magic string.
- The command palette gets "Meglepetés" / "Surprise me": it navigates to Home and
  rerolls the hero on arrival. No second "Mit nézzek?" row beside it — the Home
  module row already matches that phrase through its descriptive title.
- A global Shift+W jumps to Home. A chord, not a bare `w`: the Plex player binds bare
  letters and `w` sits on `s`, so a blind reach for the subtitle key would have thrown
  a viewer out of the film.

The palette's request crosses a lazy module boundary, so it is a token that waits
(lib/homeIntent) rather than an event fired into an empty room. Browser-measured:
taken with a compare-and-clear, because StrictMode's double-invoked mount effect
otherwise rerolled twice and landed on the page two picks deep.

HU/EN parity kept; UAT on localdev in both languages, including the empty shelf.

frontend/src/lib/keymap.test.ts

@@ -146,6 +146,7 @@ describe("dispatch", () => {
     const handlers = {
       help: () => void calls.push("help"),
       palette: () => void calls.push("palette"),
+      home: () => void calls.push("home"),
     };
     expect(dispatch(press({ key: "F10", shiftKey: true }), "global", handlers)).toBe(false);
     expect(dispatch(press({ key: "ContextMenu" }), "global", handlers)).toBe(false);