feat: (DNM) add async support to S2 Menu

[LFDanLu]

Adds async loading support to S2 Menu. Similar behavior as existing S2 components (Picker/Combobox)

✅ Pull Request Checklist:

• Included link to corresponding React Spectrum GitHub Issue.
• Added/updated unit tests and storybook for this change (for new code or code which already has tests).
• Filled out test instructions.
• Updated documentation (if it already exists for this component).
• Looked at the Accessibility Practices for this feature - Aria Practices
• I understand every change in this PR and can explain why it's there.
• If AI-assisted, I followed our AI contribution guidance and pointed my assistant at CLAUDE.md.

📝 Test Instructions:

Test S2 Menu async docs and story

🧢 Your Project:

RSP

[rspbot]

Build successful! 🎉

• View the storybook
• View the S2 storybook
• View the S2 docs
• View the React Aria docs

[rspbot]

Build successful! 🎉

• View the storybook
• View the S2 storybook
• View the S2 docs
• View the React Aria docs

[snowystinger]

Looks good, a couple small items

[rspbot]

Build successful! 🎉

• View the storybook
• View the S2 storybook
• View the S2 docs
• View the React Aria docs

[rspbot]

## API Changes

@react-spectrum/s2

/@react-spectrum/s2:Menu

 Menu <T> {
   UNSAFE_className?: UnsafeClassName
   UNSAFE_style?: CSSProperties
   aria-describedby?: string
   aria-details?: string
   aria-label?: string
   aria-labelledby?: string
   autoFocus?: boolean | FocusStrategy
   children: ReactNode | (T) => ReactNode
   defaultSelectedKeys?: 'all' | Iterable<Key>
   dependencies?: ReadonlyArray<any>
   disabledKeys?: Iterable<Key>
   disallowEmptySelection?: boolean
   escapeKeyBehavior?: 'clearSelection' | 'none' = 'clearSelection'
   hideLinkOutIcon?: boolean
   id?: string
   items?: Iterable<T>
+  loadingState?: LoadingState
   onAction?: (Key, T) => void
   onClose?: () => void
+  onLoadMore?: () => any
   onSelectionChange?: (Selection) => void
   selectedKeys?: 'all' | Iterable<Key>
   selectionMode?: SelectionMode
   shouldCloseOnSelect?: boolean
   size?: 'S' | 'M' | 'L' | 'XL' = 'M'
   slot?: string | null
   styles?: StylesProp
 }

/@react-spectrum/s2:MenuProps

 MenuProps <T> {
   UNSAFE_className?: UnsafeClassName
   UNSAFE_style?: CSSProperties
   aria-describedby?: string
   aria-details?: string
   aria-label?: string
   aria-labelledby?: string
   autoFocus?: boolean | FocusStrategy
   children: ReactNode | (T) => ReactNode
   defaultSelectedKeys?: 'all' | Iterable<Key>
   dependencies?: ReadonlyArray<any>
   disabledKeys?: Iterable<Key>
   disallowEmptySelection?: boolean
   escapeKeyBehavior?: 'clearSelection' | 'none' = 'clearSelection'
   hideLinkOutIcon?: boolean
   id?: string
   items?: Iterable<T>
+  loadingState?: LoadingState
   onAction?: (Key, T) => void
   onClose?: () => void
+  onLoadMore?: () => any
   onSelectionChange?: (Selection) => void
   selectedKeys?: 'all' | Iterable<Key>
   selectionMode?: SelectionMode
   shouldCloseOnSelect?: boolean
   size?: 'S' | 'M' | 'L' | 'XL' = 'M'
   slot?: string | null
   styles?: StylesProp
 }

---

[rspbot]

Agent Skills Changes

Modified (10)

• react-aria/agent-skills/index.json $\color{green}{+1}$ $\color{red}{-1}$
• react-aria/agent-skills/react-aria.tar.gz
• react-aria/agent-skills/react-aria/references/components/Separator/useSeparator.md $\color{green}{+1}$ $\color{red}{-1}$
• s2/agent-skills/index.json $\color{green}{+3}$ $\color{red}{-3}$
• s2/agent-skills/migrate-react-spectrum-v3-to-s2.tar.gz
• s2/agent-skills/react-spectrum-s2.tar.gz
• s2/agent-skills/react-spectrum-s2/references/components/Menu.md $\color{green}{+49}$
• s2/agent-skills/react-spectrum-s2/references/guides/ai-components.md $\color{red}{-17}$
• s2/agent-skills/react-spectrum-s2/references/react-aria/components/Separator/useSeparator.md $\color{green}{+1}$ $\color{red}{-1}$
• s2/agent-skills/spectrum-audit.tar.gz

Install

React Spectrum S2:

npx skills add https://d1pzu54gtk2aed.cloudfront.net/pr/ee11e1a87cdfb239e9b8740603bd088b99dfd732/

React Aria:

npx skills add https://d5iwopk28bdhl.cloudfront.net/pr/ee11e1a87cdfb239e9b8740603bd088b99dfd732/

[LFDanLu]

DNM until we release the AI package. Then we can merge and coworker can operate off a nightly