feat: Structure tailwind CSS styling for reusability

[handreyrc]

Description

Like regular CSS, it is possible to override and group tailwind styles into reusable classes defined in a CSS file.

Motivation

It is preferable to centralize and group css styling into reusable classes making it easier to reuse, maintain and keep the code free from long and complex inline styling.

Proposed Implementation

• Group react flow overriden styles and into a layer
• Strutrure current styling into 'layers' per component / purpose.
• Ensure tailwind styling is resposive to light and dark themes.

Definition of Done

• Implementation: No overlaps, node selection / deselection / hover behaviors are preserved and styling is responsive to theme changes.
• 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.