phsl / new-api

Hide y-axis scrollbars to provide a cleaner UI experience while maintaining
scroll functionality through mouse wheel and keyboard navigation.

Changes include:
- Hide scrollbars in CustomRequestEditor TextArea component
- Hide scrollbars in chat container and all related chat components
- Hide scrollbars in thinking content areas
- Add cross-browser compatibility for scrollbar hiding
- Maintain scroll functionality while improving visual aesthetics

Components affected:
- CustomRequestEditor.js: Added custom-request-textarea class
- index.css: Updated scrollbar styles for chat, thinking, and editor areas

The interface now provides a more streamlined appearance consistent with
modern UI design patterns while preserving all interactive capabilities.