domain: player/reporting ticks -> milliseconds (phase 4c)

Playback position now crosses the IPC boundary in milliseconds. Ticks
survive only inside Rust (DB storage, Jellyfin API) and at the genuine
remote-session boundary (session seek / transfer / RemoteControls).

Rust command signatures (ms in, converted to ticks internally):
- storage_update_playback_progress / _context: position_ms
- repository_report_playback_start / _progress / _stopped: position_ms
- PlaybackProgress.position_ticks -> position_ms (converted in the query)

Frontend:
- playbackReporting, playerEvents, VideoPlayer, Queue, player/[id] resume:
  seconds*1000 / durationMs/1000 instead of tick math.
- repository-client + syncService param names -> positionMs.
- Tests updated to ms fixtures/assertions.

Out of scope (legitimately ticks): NowPlayingItem, PlayState.positionTicks,
sessionSeek, playbackModeTransferToLocal, RemoteControls, SessionCard — the
remote Jellyfin session API.

Rust 456, frontend 644, check clean.

src/lib/services/playerEvents.ts

@@ -170,7 +170,7 @@ function handlePositionUpdate(position: number, duration: number): void {
  * with 0 when runTimeTicks is missing (which would zero the slider's max).
  */
 function resolveDuration(currentItem: MediaItem, isSameTrack: boolean): number {
-  const estimate = currentItem.runTimeTicks ? currentItem.runTimeTicks / 10000000 : 0;
+  const estimate = currentItem.durationMs ? currentItem.durationMs / 1000 : 0;
   if (isSameTrack) {
     const live = get(playbackDuration);
     if (live > 0) {