Add List support

[Kyle-Ye]

Summary

Add public List support for static and data-driven row content.

Scope

• Add the public List container API and common initializers.
• Support row composition with ForEach and dynamic content updates.
• Integrate with existing list-adjacent APIs such as ListStyle and EditMode.
• Establish baseline behavior for row layout, separators, selection/editing hooks, and styling.

Acceptance criteria

• Static List { ... } content renders as rows.
• Data-driven List/ForEach content preserves identity across updates.
• Basic list styling and edit-mode behavior have tests or examples.