feat: Update Storybook setup and apply project styling

[lornakelly]

Description

Remove default Storybook boilerplate, including welcome pages, example stories, and placeholder content. Update Storybook to reflect the editor project, applying appropriate styling and structure (TBD). Use KIE Tools Storybook as a reference for layout and organisation.

Motivation

Provide a cleaner, more relevant development environment that better reflects the actual editor and improves usability for development and demos

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.