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.regression.test.ts

@@ -73,8 +73,8 @@ function makeItem(overrides: Partial<MediaItem> = {}): MediaItem {
   return {
     id: "track-1",
     name: "Test Track",
-    type: "Audio",
-    runTimeTicks: null,
+    kind: "track",
+    durationMs: null,
     ...overrides,
   } as MediaItem;
 }
@@ -102,7 +102,7 @@ describe("Player Events — pause must not zero the slider duration", () => {
   it("preserves the live duration across pause when runTimeTicks is missing", async () => {
     // runTimeTicks is null — the previous code recomputed duration as 0 here,
     // which collapsed the slider's max and snapped the thumb to the start.
-    const item = makeItem({ runTimeTicks: null });
+    const item = makeItem({ durationMs: null });
     currentQueueItemStore.set(item);
 
     const { initPlayerEvents } = await import("./playerEvents");
@@ -130,8 +130,8 @@ describe("Player Events — pause must not zero the slider duration", () => {
   });
 
   it("falls back to the runTimeTicks estimate when no live duration is known yet", async () => {
-    // 70s in ticks (1 tick = 100ns) → 700_000_000.
-    const item = makeItem({ runTimeTicks: 700_000_000 });
+    // 70 seconds = 70_000 ms.
+    const item = makeItem({ durationMs: 70_000 });
     currentQueueItemStore.set(item);
 
     const { initPlayerEvents } = await import("./playerEvents");