refactor(format): consolidate duration formatters into format/formatDuration (Phase L, part 2) (#690)

The mm:ss track-time formatter was hand-rolled in 11 places and the
h:mm:ss total-duration formatter in 4 — extract two tested functions:

- formatTrackTime(seconds, fallback='0:00')  — m:ss, used for track /
  playback times. fallback param covers the '–' placeholder rows.
- formatLongDuration(seconds)                — h:mm:ss when >=1h, else
  m:ss, used for album / queue totals.

Behaviour preserved per call site: the unified guard
(!seconds || !isFinite || <0 -> fallback) produces identical output to
every prior variant for all real inputs; SongRow keeps its '–' via the
fallback arg. Removes the formatter exports from 6 componentHelpers
files (playerBarHelpers / fullscreenPlayerHelpers deleted — they only
exported the formatter) and 7 inline component copies.

+ formatDuration.test.ts

src/utils/format/formatDuration.ts

@@ -0,0 +1,23 @@
+/**
+ * `m:ss` track time from a seconds value. Non-positive / non-finite input
+ * returns `fallback` (default `'0:00'`; pass e.g. `'–'` for placeholder rows).
+ */
+export function formatTrackTime(seconds: number, fallback = '0:00'): string {
+  if (!seconds || !isFinite(seconds) || seconds < 0) return fallback;
+  const m = Math.floor(seconds / 60);
+  const s = Math.floor(seconds % 60);
+  return `${m}:${s.toString().padStart(2, '0')}`;
+}
+
+/**
+ * `h:mm:ss` when the duration reaches an hour, otherwise `m:ss`. Used for
+ * album / queue totals. Non-positive / non-finite input returns `'0:00'`.
+ */
+export function formatLongDuration(seconds: number): string {
+  if (!seconds || !isFinite(seconds) || seconds < 0) return '0:00';
+  const h = Math.floor(seconds / 3600);
+  const m = Math.floor((seconds % 3600) / 60);
+  const s = Math.floor(seconds % 60);
+  if (h > 0) return `${h}:${m.toString().padStart(2, '0')}:${s.toString().padStart(2, '0')}`;
+  return `${m}:${s.toString().padStart(2, '0')}`;
+}