feat(settings): clock format setting (Auto / 24h / 12h) (#742)

* feat(settings): clock format setting (Auto / 24h / 12h)

Reported on the Psysonic Discord — the Queue side panel's ETA label
and the sleep-timer preview both render via `formatClockTime`, which
just calls `toLocaleTimeString` and so follows the user's system
locale. On en-US that means AM/PM, with no in-app way out.

Add a tri-state **Clock Format** setting under
**Settings → System → App Behavior**:

* `auto` (default) — keep the existing locale-driven behaviour, so
  bestehende installs are unaffected on first launch.
* `24h` — force 24-hour wall-clock output everywhere
  `formatClockTime` is used.
* `12h` — force AM/PM output.

Wired through `authStore` (`clockFormat`, `setClockFormat`), exposed
via `CustomSelect` in `SystemTab`, and threaded into the two
consumers (`QueueHeader`, `PlaybackDelayModal`) so they re-render on
change. `formatClockTime` itself stays a pure helper — it accepts the
setting as an optional second argument and maps it to `hour12`.

Locale coverage: all nine bundled locales (en, de, es, fr, nl, nb,
ru, zh, ro) get the four new settings strings. Pin tests added for
the `setClockFormat` setter and the `hour12` mapping in
`formatClockTime`.

* docs(changelog): clock format setting + contributors (PR #742)

src/components/PlaybackDelayModal.tsx

@@ -3,6 +3,7 @@ import { createPortal } from 'react-dom';
 import { X, Moon, Sunrise } from 'lucide-react';
 import { useTranslation } from 'react-i18next';
 import { usePlayerStore } from '../store/playerStore';
+import { useAuthStore } from '../store/authStore';
 import { useShallow } from 'zustand/react/shallow';
 
 import type { TFunction } from 'i18next';
@@ -153,9 +154,10 @@ export default function PlaybackDelayModal({ open, onClose, anchorRef }: Playbac
 
   // Live preview: seconds that would be applied right now if the user clicked.
   // Priority: hovered chip → typed custom minutes → nothing.
+  const clockFormat = useAuthStore(s => s.clockFormat);
   const previewSeconds = hoverSeconds ?? customSeconds;
   const previewAtMs = previewSeconds != null ? nowTick + previewSeconds * 1000 : null;
-  const previewClock = previewAtMs != null ? formatClockTime(previewAtMs) : null;
+  const previewClock = previewAtMs != null ? formatClockTime(previewAtMs, clockFormat) : null;
 
   if (!open) return null;