Add preview card component from Base UI

[devin-ai-integration]

Update all preview card prop descriptions with official Base UI documentation

Summary

This PR comprehensively updates all prop descriptions across all PreviewCard components to match the official Base UI documentation. The changes ensure accuracy, consistency, and completeness of component documentation by sourcing descriptions directly from the official Base UI JSON documentation files.

Key improvements:

• Accurate descriptions: All prop descriptions now match the official Base UI documentation exactly
• Consistent render prop descriptions: All components with render props use the same official description format
• Default values: Updated to reflect official Base UI defaults (e.g., align: "center", side: "bottom", delay: 600ms)
• Comprehensive coverage: Added missing descriptions for all render props across 7 components
• Format consistency: Maintained established comment format while improving accuracy

Review & Testing Checklist for Human

• Cross-reference prop descriptions with official Base UI docs - Verify descriptions match Base UI PreviewCard JSON files exactly, especially default values and technical details
• Test component functionality thoroughly - Verify the preview card still works correctly with hover delays, positioning, and content rendering after description updates
• Validate description consistency - Ensure all render prop descriptions are identical across components and follow the established format pattern

Recommended test plan: Test the preview card component in the demo application with various configurations (different positions, delays, content types) to ensure functionality remains intact after documentation updates.

---

Diagram

%%{ init : { "theme" : "default" }}%%
graph TD
    A["Base UI JSON<br/>Documentation Files"]:::context --> B["reflex_ui/components/base/<br/>preview_card.py"]:::major-edit
    B --> C["PreviewCardRoot<br/>prop descriptions"]:::major-edit
    B --> D["PreviewCardTrigger<br/>prop descriptions"]:::major-edit
    B --> E["PreviewCardPortal<br/>prop descriptions"]:::major-edit
    B --> F["PreviewCardPositioner<br/>prop descriptions"]:::major-edit
    B --> G["PreviewCardPopup<br/>prop descriptions"]:::major-edit
    B --> H["PreviewCardArrow<br/>prop descriptions"]:::major-edit
    B --> I["PreviewCardBackdrop<br/>prop descriptions"]:::major-edit
    J["demo/demo/demo.py"]:::context --> K["Component Testing"]:::context
    
    A -.->|"sourced from"| B
    J -.->|"validates"| B
    
    subgraph Legend
        L1["Major Edit"]:::major-edit
        L2["Minor Edit"]:::minor-edit  
        L3["Context/No Edit"]:::context
    end
    
    classDef major-edit fill:#90EE90
    classDef minor-edit fill:#87CEEB
    classDef context fill:#FFFFFF

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Notes

• Comprehensive update: All 7 PreviewCard components updated with official Base UI descriptions
• Testing completed: Component functionality verified in demo application - hover interaction works correctly
• CI status: All pre-commit checks passed (ruff, codespell, pyright)
• Documentation source: Descriptions sourced from official Base UI JSON files at https://github.com/mui/base-ui/blob/master/docs/reference/generated/
• Consistency maintained: All render prop descriptions use identical official Base UI text
• Session requested by Carlos Cutillas (carlos@reflex.dev) - Link to Devin run

[devin-ai-integration]

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