✨ feat: Add skeleton loading animation to SelectableButtonGroup component (#1365)

Add comprehensive loading state support with skeleton animations for the SelectableButtonGroup component, improving user experience during data loading.

Key Changes:
- Add loading prop to SelectableButtonGroup with minimum 500ms display duration
- Implement skeleton buttons with proper Semi-UI Skeleton wrapper and active animation
- Use fixed skeleton count (6 items) to prevent visual jumping during load transitions
- Pass loading state through all pricing filter components hierarchy:
  - PricingSidebar and PricingFilterModal as container components
  - PricingDisplaySettings, PricingCategories, PricingGroups, PricingQuotaTypes as filter components

Technical Details:
- Reference CardTable.js implementation for consistent skeleton UI patterns
- Add useEffect hook for 500ms minimum loading duration control
- Support both checkbox and regular button skeleton modes
- Maintain responsive layout compatibility (mobile/desktop)
- Add proper JSDoc parameter documentation for loading prop

Fixes:
- Prevent skeleton count sudden changes that caused visual discontinuity
- Ensure proper skeleton animation with Semi-UI active parameter
- Maintain consistent loading experience across all filter components

web/src/components/table/model-pricing/modal/PricingFilterModal.jsx

@@ -44,6 +44,7 @@ const PricingFilterModal = ({
     setFilterGroup,
     filterQuotaType,
     setFilterQuotaType,
+    loading,
     ...categoryProps
   } = sidebarProps;
 
@@ -105,16 +106,18 @@ const PricingFilterModal = ({
           setCurrency={setCurrency}
           showRatio={showRatio}
           setShowRatio={setShowRatio}
+          loading={loading}
           t={t}
         />
 
-        <PricingCategories {...categoryProps} setActiveKey={setActiveKey} t={t} />
+        <PricingCategories {...categoryProps} setActiveKey={setActiveKey} loading={loading} t={t} />
 
         <PricingGroups
           filterGroup={filterGroup}
           setFilterGroup={setFilterGroup}
           usableGroup={categoryProps.usableGroup}
           models={categoryProps.models}
+          loading={loading}
           t={t}
         />
 
@@ -122,6 +125,7 @@ const PricingFilterModal = ({
           filterQuotaType={filterQuotaType}
           setFilterQuotaType={setFilterQuotaType}
           models={categoryProps.models}
+          loading={loading}
           t={t}
         />
       </div>