fix(studio): remove duplicate useSdkSession call from App.tsx

Cherry-pick of af1d91b (dispose race fix) added a second
useSdkSession call at the original insertion point from s7step1.
s7step3c already had the correct call (with domEditSaveTimestampRef
for self-write suppression) at line 156. Remove the duplicate.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Co-authored-by: Miguel Ángel <miguel07alm@protonmail.com>

Author: vanceingalls

packages/studio/src/App.tsx

@@ -269,7 +269,6 @@ export function StudioApp() {
     () => leftSidebarRef.current?.getTab() ?? "compositions",
     [],
   );
-  const sdkSession = useSdkSession(projectId, activeCompPath);
   const domEditSession = useDomEditSession({
     projectId,
     activeCompPath,