refactor(studio): single-source timeline selection id-resolution

The DOM-selection to timeline sync routes through the canonical resolveTimelineIdForSelection
(source-file, ancestor, active-comp fallback) instead of a narrow domId/id match that
mismatched sub-composition clips.

The preview-sync equality check compares selection as sets both ways and includes the
anchor, so duplicate resolutions no longer mask an unsynced member.

packages/studio/src/hooks/useDomEditWiring.ts

@@ -11,6 +11,7 @@ import { useCallback, useEffect, useRef } from "react";
 import type { DomEditSelection } from "../components/editor/domEditingTypes";
 import { STUDIO_GSAP_PANEL_ENABLED } from "../components/editor/manualEditingAvailability";
 import { usePlayerStore } from "../player";
+import { resolveTimelineIdForSelection } from "../utils/studioHelpers";
 import { useDomEditPreviewSync } from "./useDomEditPreviewSync";
 import { useGsapAnimationsForElement, usePopulateKeyframeCacheForFile } from "./useGsapTweenCache";
 import { useGsapAnimationFetchFallback } from "./useGsapAnimationFetchFallback";
@@ -171,12 +172,12 @@ export function useDomEditWiring({
   useEffect(() => {
     if (!domEditSelection?.id) return;
     const { selectedElementId, elements, setSelectedElementId } = usePlayerStore.getState();
-    const matchKey = elements.find(
-      (el) => el.domId === domEditSelection.id || el.id === domEditSelection.id,
-    );
-    const key = matchKey ? (matchKey.key ?? matchKey.id) : null;
+    // Resolve through the canonical resolver (source-file + ancestor + active-comp
+    // fallback) rather than a narrow domId/id match, so a sub-composition selection
+    // maps to the same clip the rest of the selection pipeline picks.
+    const key = resolveTimelineIdForSelection(domEditSelection, elements, activeCompPath);
     if (key && key !== selectedElementId) setSelectedElementId(key);
-  }, [domEditSelection?.id]);
+  }, [domEditSelection, activeCompPath]);
 
   // ── GSAP cache sync ──