fix(tabs): complete interaction, overflow, and sizes

[tbielich]

Summary

• implement horizontal and vertical roving focus
• support Arrow, Home, End, Enter, and Space behavior
• synchronize selected tabs with controlled panels
• add scroll and wrap overflow modes
• add default and compact sizes
• remove the unrelated panel scroll-snap behavior
• dispatch a bubbling uif-tab-change event
• update documentation and add contract-level unit coverage
• add a Code Connect schema placeholder for the published Figma node ID

Issue

Closes #36

Boundaries

• no Table changes
• no routing/navigation-tab behavior
• Code Connect requires replacing TABS-NODE-ID after Figma publication

Validation

• disabled tabs are skipped by keyboard navigation
• orientation controls the arrow-key axis
• activation updates aria-selected, tabindex, and panel visibility
• overflow and size contracts are covered by tests
• documented behavior now matches Runtime behavior