fix(workflow-form): a result update rebuilds the visualization frame on every emission #8759

What happened?

The Form View keys each chart frame by a per-operator resultVersion and bumps it for every operator in every getResultUpdateStream() emission (workflow-form.component.ts:349-357). Each bump changes the frame's *ngFor identity, so the visualization iframe is destroyed and recreated on every update. That defeats VisualizationFrameContentComponent's own throttled (auditTime 2 s) in-place self-update: during a run the chart flickers and re-fits on each emission instead of updating in place.

The key exists for a reason (#8441): the chart reads its content once at creation, and a reused frame showed "undefined" for a genuinely new result.

Expected: the frame is rebuilt only when a result is genuinely new -- its first appearance, or a re-run -- and updates in place otherwise. clearResults is a separate stream and has to be handled so a re-run still gets a fresh frame, without bringing the stale/undefined-picture bug back.

Part of #8439 (the result-frame rebuild churn item) and the Form View feature #8011. From the #8441 review.

How to reproduce?

1. Open a workflow in the Form View whose shown result is a visualization, on a run that emits many result updates (a slow pipeline).
2. Watch the chart during the run: it is recreated on each emission (the iframe element's identity changes; the frame's content request repeats) rather than updating in place.

Has to be verified on a flag-on instance: the iframe cannot render in jsdom, so the unit tests can only pin when the key changes.

Version/Branch

1.4.0-incubating-SNAPSHOT (main)

Commit Hash (Optional)

506397a

What browsers are you seeing the problem on?

Chrome

Relevant log output

No response