fix(studio): wire Grade rollback through the real commit path, scope async completions

Fixes two of the three adversarial findings from the second #2416 tip
re-review; the third is a pre-existing runtime-protocol gap, explained in
the PR thread rather than patched here.

- The Grade rollback added in the previous commit could never fire through
  the real Studio callback: runDomEditCommit (the shared commit runner used
  by every data-attribute commit, not just Grade) catches persist failures
  internally and always resolves, reporting outcome only via its own
  onError side effect. A caller awaiting the promise never sees a
  rejection, so the revert-on-reject logic was dead code against the
  actual app. Added an optional onSettled(ok) callback to
  DomEditCommitRunnerConfig (purely additive — every existing caller that
  doesn't pass it is unaffected) and threaded it through
  commitDataAttribute -> handleDomAttributeLiveCommit -> the
  onSetAttributeLive prop type (now accepts an optional 3rd argument)  ->
  useColorGradingController, which now drives the revert from the real
  signal. The promise-rejection path stays as a fallback for any other
  implementation of onSetAttributeLive that rejects instead.

- Selection flushing performed a real side effect (writing the outgoing
  element's pending edit) during the render-phase identity-reset block.
  Adjusting STATE during render (comparing against a ref) is React's
  documented pattern, but it doesn't license actual I/O — React can invoke
  render more than once per commit, which could double-fire or misorder
  the write. The reset block now only enqueues the flush (a pure ref
  write); a new effect keyed on the identity performs it after commit.

- Async persist completions (both the onSettled callback and its promise-
  rejection fallback) now capture the identity key the attempt was made
  for and check it against the CURRENT identity before touching
  confirmedGradingRef/grading/runtimeStatus. Without this, a persist that
  settles after selection has moved on to a THIRD element could clobber
  that element's freshly-reset state with a result that belongs to an
  element no longer selected.

Not fixed here: the runtime Grade target (HfColorGradingTarget, used by
core's resolveTarget to find the DOM element inside the preview iframe)
has no source-file/composition-scope discriminator, matching the same gap
selectionIdentityKey had before this stack — but fixing it means changing
a wire-protocol type shared across core/player/studio and the legacy
ColorGradingSection too. hfId (checked first, before id/selector) is
minted uniquely per element at parse time in the common case, so this is
a narrow residual risk for hfId-less same-selector elements across
different source files, not a regression introduced by this stack.
Flagged as a follow-up in the PR thread.

New/updated regression tests: real onSettled(false) path (distinct from
the promise-rejection fallback), and a stale in-flight persist settling
after selection has moved on twice more. Full studio suite still at the
known pre-existing 55-failure baseline, zero regressions.

packages/studio/src/hooks/useDomEditAttributeCommits.ts

@@ -25,6 +25,7 @@ interface DataAttributeCommitOptions {
   coalescePrefix: string;
   skipRefresh: boolean;
   refreshAfter?: boolean;
+  onSettled?: (ok: boolean) => void;
 }
 
 function resolveFullAttrName(attr: string, prefixData: boolean | undefined): string {
@@ -128,6 +129,7 @@ export function useDomEditAttributeCommits({
         onError: (error) => reportDomEditPersistFailure(domEditSelection, [op], error, showToast),
         shouldResync: () => isLatestCommit() && !!options.refreshAfter,
         resync: () => refreshDomEditSelectionFromPreview(domEditSelection),
+        onSettled: options.onSettled,
       });
     },
     [
@@ -153,11 +155,12 @@ export function useDomEditAttributeCommits({
   );
 
   const handleDomAttributeLiveCommit = useCallback(
-    async (attr: string, value: string | null) => {
+    async (attr: string, value: string | null, onSettled?: (ok: boolean) => void) => {
       await commitDataAttribute(attr, value, {
         label: `Edit ${attr.replace(/^(data-)?/, "").replace(/-/g, " ")}`,
         coalescePrefix: "attr-live",
         skipRefresh: true,
+        onSettled,
       });
     },
     [commitDataAttribute],