Fix Core Areas carousel selection overwrite

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Summary

• Prevent debounced carousel scroll-sync from overriding explicit click/keyboard tab selections after scrollIntoView settles.
• Keep passive swipe/scroll synchronization unchanged.

Validation

• Reproduced pre-fix at 480px (AI Penetration Testing reverted to Thick Clients) and 1024px (Thick Clients reverted to Web3 / Blockchain Security).
• Headless Chrome regression sweep passed across 280, 320, 360, 375, 390, 414, 480, 640, 768, and 1024px for every Core Areas tab.
• Settled manual carousel scroll-sync check passed at 375, 480, and 1024px.
• Static smoke passed for 5 HTML files, 2 inline scripts, local refs/assets, duplicate IDs, _blank rel safety, and #focusPanel visibility.