[RFC] feat(ui5-li): add semantic click event to ListItemBase

[ilhan007]

Summary

• Adds a public click CustomEvent to ListItemBase, enabling framework consumers (React, Angular, Vue) to attach onClick handlers directly on list items (<ListItemStandard onClick={...}>) instead of relying on the parent container's item-click event
• Event detail includes item (the ListItemBase instance) and originalEvent (the underlying mouse/keyboard event), matching the Button's semantic click pattern
• Native click from shadow DOM <li> is stopped via stopPropagation() to prevent duplicate events reaching consumers
• All components extending ListItemBase inherit this behavior: ListItemStandard, MenuItem, TreeItem, NotificationListItem, UploadCollectionItem, etc.

Resolves #13304

Changes

packages/main/src/ListItemBase.ts

• Added @event("click", { bubbles: true }) decorator
• Added ListItemBaseClickEventDetail type with item and originalEvent
• fireItemPress() now fires fireDecoratorEvent("click", { item, originalEvent }) alongside existing _press
• _onclick() calls e.stopPropagation() before fireItemPress() to suppress native click from shadow DOM

Test plan

• List.cy.tsx — 5 new tests (click, Enter, Space, disabled, backward compat with item-click)
• Menu.cy.tsx — 3 new tests (click, Enter, backward compat with item-click)
• Tree.cy.tsx — 5 new tests (click, Enter, Space, disabled, backward compat with item-click)
• Tests listen for "click" (not "ui5-click") and assert calledOnce to verify no duplicate native+semantic events
• All existing tests pass (92 List, 41 Menu, 26 Tree)
• Lint passes

[ui5-webcomponents-bot]

🚀 Deployed on https://pr-13315--ui5-webcomponents-preview.netlify.app