Enable full child rendering in WorkspaceComponent spec

[Yicong-Huang]

Task Summary

WorkspaceComponent's unit spec currently overrides the template to a minimal <div #codeEditor> so the heavyweight children (CodeEditorComponent, workflow editor, panels, etc.) don't compile in the test build. As a result, the spec cannot verify side effects that depend on real child rendering.

The blocker is CodeEditorComponent — its own spec has unresolved issues. Plan:

1. Fix CodeEditorComponent spec first.
2. Remove the template override from WorkspaceComponent spec so real children render.
3. Extend coverage to the child-driven side effects (e.g. editor lifecycle wiring).

Tracking deferral noted in #4969 review.

Task Type

• Testing / QA

[Ma77Ball]

/take