Unify operator border-coloring so a newly-added operator is validated and painted once

[PG1204]

Task Summary

When an operator is newly added, its border is currently validated and painted twice, once by the operator-add stream subscriber and once by the validation stream that fires shortly after. This task unifies the two border-coloring paths in WorkflowEditorComponent so a newly-added operator is validated and painted exactly once, while preserving the navigation-reset restore behavior from #3614.

Context

WorkflowEditorComponent.applyOperatorBorder decides an operator's border color (invalid -> red, valid + cached run status -> state color, valid + no status -> default gray). It has two callers:

• handleOperatorValidation: the validation-stream subscriber, which already has the Validation result and passes it in.
• The operator-add stream subscriber: which has no Validation in hand and relies on the helper recomputing it.

These run off two separate event streams. As a result, when an operator is newly added, it ends up validated and its border painted twice:

1. The operator-add subscriber fires (getOperatorAddStream) -> paints the border using a freshly-computed validation.
2. A moment later, validation for the new operator runs via getOperatorDynamicSchemaChangedStream -> operatorValidationStream fires → handleOperatorValidation paints the border again.

Raised as a follow-up suggestion during review of the applyOperatorBorder optimization (PR #).

Proposed change

Unify the two paths so a newly-added operator is validated and painted exactly once, ideally with both callers obtaining the Validation the same way, allowing the optional-parameter fallback in applyOperatorBorder to be removed.

In frontend/src/app/workspace/component/workflow-editor/workflow-editor.component.ts.

Considerations

• The operator-add subscriber was added for the navigation-reset fix (Operator Status Color Resets After Page Navigation #3614): when the user navigates back to a workflow, reloadWorkflow re-adds every operator and the border (plus cached run status) must be restored immediately. Any unification must preserve that the border can't be left blank waiting on a later validation event.
• This is a non-functional cleanup; behavior should be unchanged. Existing tests in workflow-editor.component.spec.ts (the "operator border restoration after navigation" block) should continue to pass, with coverage added for the single-paint behavior.

Related

• PR fix(frontend): preserve operator state border on workflow page return #5146 (introduced applyOperatorBorder and the Operator Status Color Resets After Page Navigation #3614 navigation fix)
• PR refactor(frontend): avoid redundant validateOperator call in applyOperatorBorder #5702 (added the optional Validation parameter; this issue was raised in its review)

Task Type

• Refactor / Cleanup
• DevOps / Deployment / CI
• Testing / QA
• Documentation
• Performance
• Other

[PG1204]

/take