Add Base UI accordion component with high-level wrapper

[devin-ai-integration]

Add Base UI accordion component with high-level wrapper

Summary

This PR implements a complete Base UI accordion component wrapper for reflex-ui, following the established patterns used by other components like tooltip and select. The implementation includes:

• Individual components: AccordionRoot, AccordionItem, AccordionHeader, AccordionTrigger, AccordionPanel
• High-level wrapper: HighLevelAccordion that accepts trigger and content props as requested
• Component namespace: Both compositional API (accordion.root(), accordion.item()) and high-level API (accordion())
• Base UI integration: Proper library configuration with @base_ui/react/accordion
• Lazy loading: Added to the reflex-ui lazy loader system
• Demo integration: Added accordion example to demo app

The component was tested locally and confirmed to work with proper expand/collapse functionality.

Review & Testing Checklist for Human

• Verify accordion animations work correctly - Test that expand/collapse transitions are smooth and follow the expected Base UI behavior
• Test high-level API with different content types - Try passing both string and component content to ensure flexibility
• Check component styling matches design system - Verify the Tailwind classes produce the expected accordion appearance
• Test compositional API - Ensure accordion.root(), accordion.item(), etc. work for advanced use cases
• Verify multiple accordions work - Test rendering multiple accordion instances on the same page

Recommended test plan: Run the demo app, interact with the accordion, try creating custom accordion layouts using both high-level and compositional APIs.

---

Diagram

%%{ init : { "theme" : "default" }}%%
graph TD
    A["reflex_ui/__init__.py"]:::major-edit --> B["components/base/accordion.py"]:::major-edit
    A --> C["components/base/tooltip.py"]:::context
    B --> D["Base UI accordion library"]:::context
    B --> E["BaseUIComponent"]:::context
    F["demo/demo/demo.py"]:::minor-edit --> A
    G["Browser Test"]:::context --> F
    
    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

• Prop descriptions: Sourced from Base UI JSON documentation files for accuracy
• CSS classes: Follow existing patterns from tooltip/select components but may need refinement for optimal accordion styling
• Testing: Basic functionality verified in browser, but edge cases and styling details need human verification
• API design: High-level wrapper follows the same pattern as HighLevelCollapsible for consistency

Session requested by: Carlos Cutillas (carlos@reflex.dev)
Link to Devin run: https://app.devin.ai/sessions/e21529f7d4eb4e66bd03e34ad963fbe4

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