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/syncService.ts

@@ -104,12 +104,12 @@ class SyncService {
    */
   async queuePlaybackProgress(
     itemId: string,
-    positionTicks: number
+    positionMs: number
   ): Promise<number> {
     // Update local state first
-    await commands.storageUpdatePlaybackProgress(auth.getUserId() ?? "", itemId, positionTicks);
+    await commands.storageUpdatePlaybackProgress(auth.getUserId() ?? "", itemId, positionMs);
 
-    return this.queueMutation("update_progress", itemId, { positionTicks });
+    return this.queueMutation("update_progress", itemId, { positionMs });
   }
 
   /**