Module lit/renderers/scDiscriminated

<sc-discriminated> — Custom Element renderer for DiscriminatedUnionField.

Implements the WAI-ARIA "Tabs with Automatic Activation" pattern in parity with React's DiscriminatedUnionTabs:

• ArrowRight / ArrowLeft move between tabs with wrap-around
• Home / End jump to the first / last tab
• role="tablist" / "tab" / "tabpanel", aria-selected, aria-controls, aria-labelledby
• Roving tabindex: the active tab carries tabindex="0", the rest tabindex="-1"
• Selection and focus stay aligned on every keystroke

Parts: tablist, tab, tab-active, panel.