feat(player): polish sleep-timer UI — circular ring + in-button countdown (#272)

Replaces the text-pill schedule badge with a circular SVG progress ring
around the play/pause button. Accent→lavender gradient stroke, counter-
clockwise depletion synced to the armed deadline, subtle accent glow.

While a timer is armed, the Play/Pause icon inside the button is
swapped for a two-line stack: a small Moon (sleep timer) or Sunrise
(delayed start) glyph above the countdown (m:ss / h:mm:ss). The icon
is the mode marker so the ring can stay unified with the rest of the
app's accent palette.

Redesigns the schedule modal with a mood-tinted header (Moon for
"Pause after", Sunrise for "Start after"), soft radial accent glow in
the background, slide-up open animation. Circular glass close-button
scoped to this modal, with hover rotation + focus ring. Custom-minutes
field gains an inline "min" suffix. A live preview line at the bottom
shows when the action fires ("Pauses at 23:47" / "Starts at 23:47"),
updating as the user hovers a preset or types. Chips gain a small
hover lift plus accent-coloured shadow.

Also fixes a pre-existing duplicate-tooltip on the play/pause button:
title= attributes removed alongside the data-tooltip (title violates
the project's "never native tooltips" rule, so both showed at once).

Adds scheduledPauseStartMs / scheduledResumeStartMs to the player
store so the progress ring has a total-duration baseline, set and
cleared alongside the existing deadline fields.

New usePlaybackScheduleRemaining hook wraps the store subscription
and 500 ms tick into a single hook used by all three player views
(PlayerBar / FullscreenPlayer / MobilePlayerView).

i18n: delayPreviewPause / delayPreviewStart keys across all 8 locales.

Co-authored-by: Psychotoxical <dev@psysonic.app>
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/utils/playbackScheduleFormat.ts

@@ -1,3 +1,7 @@
+import { useEffect, useState } from 'react';
+import { useShallow } from 'zustand/react/shallow';
+import { usePlayerStore } from '../store/playerStore';
+
 /** Remaining time until wall-clock `deadlineMs` (m:ss or h:mm:ss). */
 export function formatPlaybackScheduleRemaining(deadlineMs: number | null, nowMs: number): string {
   if (deadlineMs == null) return '';
@@ -11,3 +15,39 @@ export function formatPlaybackScheduleRemaining(deadlineMs: number | null, nowMs
   }
   return `${m}:${s.toString().padStart(2, '0')}`;
 }
+
+export interface PlaybackScheduleInfo {
+  /** Formatted countdown, e.g. "4:32". */
+  remaining: string;
+  /** Which timer is running: `pause` = sleep-timer, `start` = delayed-start. */
+  mode: 'pause' | 'start';
+}
+
+/**
+ * Hook: returns the active playback-schedule countdown + its mode, or null
+ * when no timer is armed. Ticks every 500 ms so the caller never needs to
+ * set up its own interval. Used by the play/pause button to swap the
+ * Play/Pause icon for a mode-icon + countdown text while a timer runs.
+ */
+export function usePlaybackScheduleRemaining(): PlaybackScheduleInfo | null {
+  const { isPlaying, scheduledPauseAtMs, scheduledResumeAtMs } = usePlayerStore(
+    useShallow(s => ({
+      isPlaying: s.isPlaying,
+      scheduledPauseAtMs: s.scheduledPauseAtMs,
+      scheduledResumeAtMs: s.scheduledResumeAtMs,
+    })),
+  );
+  const mode: 'pause' | 'start' | null =
+    isPlaying && scheduledPauseAtMs != null ? 'pause'
+    : !isPlaying && scheduledResumeAtMs != null ? 'start'
+    : null;
+  const deadlineMs = mode === 'pause' ? scheduledPauseAtMs : mode === 'start' ? scheduledResumeAtMs : null;
+  const [nowMs, setNowMs] = useState(() => Date.now());
+  useEffect(() => {
+    if (deadlineMs == null) return;
+    const id = window.setInterval(() => setNowMs(Date.now()), 500);
+    return () => window.clearInterval(id);
+  }, [deadlineMs]);
+  if (mode == null || deadlineMs == null) return null;
+  return { remaining: formatPlaybackScheduleRemaining(deadlineMs, nowMs), mode };
+}