feat: Styling/UX refinements

[lornakelly]

Description

As we gather feedback before release, it is likely we will need to iterate on style/UX

Motivation

Initial design/UX provide a strong foundation, but many refinements only become apparent once larger and more complex workflows are rendered in practice.

Proposed Implementation

No response

Definition of Done

• Implementation: Fully implemented according to the Serverless Workflow spec.
• Unit Tests: Comprehensive unit tests are included and passing.
• Integration Tests: Verified within the monorepo and target environments (Web/VS Code).
• Documentation: Updated README.md, ADRs, or official docs.
• Performance: No significant regression in editor responsiveness.
• Accessibility: UI changes comply with accessibility standards.