fix(studio): make static-seek adapter honor keepPlaying option (#1089)

createStaticSeekPlaybackAdapter.seek now accepts the same options as the
PlaybackAdapter contract and aligns the default-pause semantics with
wrapTimeline (hardened in 3e7b464b). Without keepPlaying the adapter
clears its `playing` flag and cancels the RAF ticker, so on non-GSAP
compositions a scrub during playback no longer leaves the iframe
silently advancing while the public seek wrapper marks isPlaying=false.

Follow-up to #863 review: jrusso called out the type drift and invited
a separate PR; this also closes the asymmetry with wrapTimeline.

Co-authored-by: Carlos Alcaraz <193642530+calcarazgre646@users.noreply.github.com>

packages/studio/src/player/lib/playbackAdapter.ts

@@ -113,12 +113,20 @@ export function createStaticSeekPlaybackAdapter(
       playing = false;
       stopTicker();
     },
-    seek: (time) => {
+    seek: (time, options) => {
       renderSeek(time);
-      if (playing) {
-        playStartTime = currentTime;
-        playStartNow = clock.now();
+      if (options?.keepPlaying) {
+        if (playing) {
+          playStartTime = currentTime;
+          playStartNow = clock.now();
+        }
+        return;
       }
+      // Default seek aligns with wrapTimeline: stop the RAF ticker so the
+      // adapter's `playing` flag matches the public seek contract instead of
+      // silently driving renderSeek in the background.
+      playing = false;
+      stopTicker();
     },
     getTime: () => currentTime,
     getDuration: () => safeDuration,