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/queuePanel/QueueHeader.tsx

@@ -2,6 +2,7 @@ import { useMemo } from 'react';
 import { ChevronDown, ListMusic } from 'lucide-react';
 import type { TFunction } from 'i18next';
 import { usePlayerStore } from '../../store/playerStore';
+import { useAuthStore } from '../../store/authStore';
 import type { Track } from '../../store/playerStoreTypes';
 import type { DurationMode } from '../../utils/componentHelpers/queuePanelHelpers';
 import { formatLongDuration } from '../../utils/format/formatDuration';
@@ -24,6 +25,7 @@ export function QueueHeader({
 }: Props) {
   const currentTime = usePlayerStore((s) => Math.floor(s.currentTime / 30) * 30);
   const isPlaying = usePlayerStore((s) => s.isPlaying);
+  const clockFormat = useAuthStore((s) => s.clockFormat);
 
   const totalSecs = useMemo(() =>
     queue.reduce((acc: number, track: Track) => acc + (track.duration || 0), 0),
@@ -40,7 +42,7 @@ export function QueueHeader({
   if (queue.length > 0) {
     if (durationMode === 'total') dur = formatLongDuration(Math.floor(totalSecs));
     else if (durationMode === 'remaining') dur = `-${formatLongDuration(Math.floor(remainingSecs))}`;
-    else dur = formatClockTime(Date.now() + remainingSecs * 1000);
+    else dur = formatClockTime(Date.now() + remainingSecs * 1000, clockFormat);
   }
 
   const nextMode: DurationMode =