refactor(ui): comprehensive combobox component optimization

[mark-karnaukh-extern-sap]

Summary

This PR introduces a comprehensive refactoring of the combobox component to improve performance, maintainability, and code organization through extensive modularization and optimization.

Changes Made

Performance Optimizations

• Removed redundant state management: Eliminated unnecessary useState and useEffect patterns that were causing performance bottlenecks
• Memoized context values: Implemented proper memoization to prevent unnecessary re-renders
• Optimized filtering and event handlers: Enhanced callback performance and filtering logic efficiency
• Added configurable debounce delay: Made debounce timing configurable as a parameter for better flexibility

Code Organization & Modularity

• Custom hooks extraction: Broke down the monolithic combobox into focused, reusable custom hooks:

  • Combobox options initialization logic
  • Floating UI logic
  • Filtering logic
  • State management logic
  • Context management logic
  • Validation logic

• Sub-component extraction: Separated complex component into smaller, focused sub-components

• Type definitions: Extracted reusable TypeScript types for better type safety

Developer Experience Improvements

• Added comprehensive documentation: Included description comments and explanation comments throughout the codebase
• Utility functions: Added CSS class merging utility for better Tailwind CSS handling
• Style management: Implemented consistent style management approach
• License headers: Added proper license headers to all files
• Code organization: Moved utilities to appropriate locations in the source structure

Technical Details

The refactoring follows modern React patterns and best practices:

• Custom hooks for separation of concerns
• Proper memoization strategies
• Optimized event handling
• Configurable component parameters
• Type-safe implementations

Testing

All existing functionality has been preserved while improving the underlying architecture. The component maintains the same public API ensuring backward compatibility.

Files Changed

• Combobox component and related UI files
• Custom hook implementations
• Utility functions
• Type definitions
• Documentation and comments

This refactoring significantly improves code maintainability, performance, and developer experience while maintaining full backward compatibility.

Related Issues

• [Task](ui): Refactor Combobox Component for Performance and Maintainability #1059

Screenshots (if applicable)

Testing Instructions

1. pnpm i
2. pnpm TASK

Checklist

• I have performed a self-review of my code.
• I have commented my code, particularly in hard-to-understand areas.
• I have added tests that prove my fix is effective or that my feature works.
• New and existing unit tests pass locally with my changes.
• I have made corresponding changes to the documentation (if applicable).
• My changes generate no new warnings or errors.
• I have created a changeset for my changes.

PR Manifesto

Review the PR Manifesto for best practises.

[changeset-bot]

🦋 Changeset detected

Latest commit: c25c982

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 9 packages

Name	Type
@cloudoperators/juno-ui-components	Patch
@cloudoperators/juno-app-carbon	Patch
@cloudoperators/juno-app-doop	Patch
@cloudoperators/juno-app-example	Patch
@cloudoperators/juno-app-greenhouse	Patch
@cloudoperators/juno-app-heureka	Patch
@cloudoperators/juno-app-supernova	Patch
@cloudoperators/juno-app-template	Patch
@cloudoperators/juno-messages-provider	Patch

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[github-actions]

PR Preview Action v1.6.1
🚀 View preview at https://cloudoperators.github.io/juno/pr-preview/pr-1041/
Built to branch gh-pages at 2025-07-02 15:53 UTC. Preview will be ready when the GitHub Pages deployment is complete.

[barsukov]

Please check the comments bellow

[ArtieReus]

It would be helpful to include a test change in one of our real applications: supernova, doop, or heureka—as part of this PR. The example app doesn’t fully replicate the behavior we have across these applications. A small, visual test in a real app will allow us to properly validate the changes. The test change can be removed once it’s been verified visually. It is enough to extend the respective Readme file.

[barsukov]

I would suggest that we could close this PR and use as tempalte for implementation on #1071 ticket