feat(react): add Waterfall masonry layout component

[wangdicoder]

Summary

• Add new Waterfall masonry layout component to @tiny-design/react
• Supports fixed or responsive column count (columns prop with breakpoint config)
• Configurable gutter spacing (number or [horizontal, vertical])
• Data-driven rendering via items + itemRender, with support for direct children content
• Items can be pinned to specific columns via column prop
• Dynamic add/remove with fade-out exit animation and smooth repositioning
• onLayoutChange callback for persisting column assignments
• Auto-measures item heights via ResizeObserver, handles image load/error
• 4 demos: Basic, Responsive (interactive slider), Image Gallery, Dynamic add/remove
• English and Chinese documentation
• 6 unit tests

Release

• Bump type: minor
• Affected packages: @tiny-design/react (fixed group bumps all packages)

Test plan

• pnpm --filter @tiny-design/react test -- --testPathPattern waterfall — 6 tests pass
• pnpm build — all packages build successfully
• pnpm dev → navigate to /components/waterfall to verify all 4 demos render correctly
• Verify responsive columns by resizing browser window
• Verify dynamic add/remove with animations

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