Feature Request: Add a Carousel component

[suxiaoshao]

Description

Add a reusable Carousel component for presenting a sequence of content panels with previous and next navigation.

GPUI Component currently provides scrolling, lists, tabs, pagination, and animation infrastructure, but it does not provide a content carousel with item selection, snapping, and carousel-specific navigation state.

Proposed scope

• Carousel root and state API
• Composable content and item parts
• Previous and next controls with disabled boundary states
• Controlled and programmatic current-index navigation
• Horizontal and vertical orientations
• Optional looping
• Pointer or trackpad dragging with item snapping
• Keyboard navigation
• Selection/change events
• Reduced-motion handling and accessibility labels

Pagination indicators can be composed from existing controls or exposed as an optional part without coupling Carousel to one visual treatment.

Reference

• shadcn/ui Carousel source

The implementation should use GPUI-native scrolling and motion behavior rather than introducing a web carousel dependency.

Acceptance criteria

• Public component and state API following existing builder conventions
• Story covering horizontal, vertical, looped, controlled, and keyboard-operated examples
• English documentation in website/docs/components/
• Chinese documentation in website/zh-CN/docs/components/
• Focused tests for navigation boundaries, looping, selection changes, and state transitions