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/components/library/EpisodeRow.svelte

@@ -1,5 +1,6 @@
 <script lang="ts">
   import { onMount } from "svelte";
+  import { truncateMiddle } from "$lib/utils/truncateMiddle";
   import type { MediaItem } from "$lib/api/types";
   import { downloads } from "$lib/stores/downloads";
   import { formatDuration } from "$lib/utils/duration";
@@ -134,7 +135,7 @@
             {episodeNumber}.
           </span>
           <h3 class="text-white font-medium truncate group-hover/row:text-[var(--color-jellyfin)] transition-colors">
-            {episode.name}
+            {truncateMiddle(episode.name, 56)}
           </h3>
           <!-- Played indicator -->
           {#if episode.userData?.isPlayed}