Wire up playback reporting, fix duration flash, hide video from audio mini player

Playback reporting (position sync / resume-on-another-device):
- player_configure_jellyfin now builds a PlaybackReporter sharing the player
  controller's Arc, so Start/Progress/Stopped actually reach Jellyfin on every
  auth path (login/restore/reauth); previously they never did.
- The PlaybackReporterWrapper now shares the same Arc the controller and MPV
  progress loop report through, instead of a dead parallel Option.
- Android position callbacks now emit throttled progress reports (30s/item),
  mirroring the MPV backend.

Duration flash on pause:
- resolveDuration() prefers the live store duration for the already-loaded
  track over the runTimeTicks estimate, so pausing no longer clobbers the
  slider's max to 0 when runTimeTicks is missing.

Video leaking into audio mini player:
- isVideoItem() also checks the backend PlayerMediaItem mediaType
  discriminator, so a video started via player_play_item (no Jellyfin `type`,
  mediaType "video") no longer surfaces in the audio mini player.

Middle-truncation of long media names:
- New truncateMiddle util applied to track/episode/card/mini-player titles so
  distinguishing tails (episode numbers, suffixes) stay visible.

Adds regression tests for the duration and mini-player fixes.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/lib/utils/truncateMiddle.ts

@@ -0,0 +1,33 @@
+/**
+ * Abbreviate a long string in the middle so both the start and the end stay
+ * visible, e.g. `long_media_name_like_this` -> `long_med…ike_this`.
+ *
+ * Unlike CSS `text-overflow: ellipsis` (which only clips the end), this keeps
+ * the tail of a media name — often the most distinguishing part (episode
+ * number, disambiguating suffix, etc.).
+ *
+ * @param value    The string to abbreviate.
+ * @param maxLength Maximum length of the returned string, including the ellipsis.
+ * @param ellipsis The separator inserted in the middle (default `…`).
+ */
+export function truncateMiddle(
+  value: string | null | undefined,
+  maxLength = 32,
+  ellipsis = "…",
+): string {
+  if (value == null) return "";
+  if (maxLength <= 0) return "";
+  if (value.length <= maxLength) return value;
+
+  // Not enough room for any real content around the ellipsis: fall back to a
+  // plain head-truncation so we never return more than maxLength characters.
+  if (maxLength <= ellipsis.length) {
+    return value.slice(0, maxLength);
+  }
+
+  const keep = maxLength - ellipsis.length;
+  const head = Math.ceil(keep / 2);
+  const tail = Math.floor(keep / 2);
+
+  return value.slice(0, head) + ellipsis + (tail > 0 ? value.slice(value.length - tail) : "");
+}