manufacturers + NAB Show naming sweep

- Standardize "NAB Show" / "2026 NAB Show" across badges, filter chips,
  and headings; never bare "NAB" in user-facing copy.
- /manufacturers/[slug]: normalize show name at render, strip
  randomstring suffix on booth, hide booth unless the show is within 90
  days, filter single-letter junk out of category display.
- News filter "NAB Show" chip loose-matches any nab-tagged article so
  legacy "NAB 2026" tags still surface.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/components/Header.tsx

@@ -619,7 +619,7 @@ export default function Header() {
                               <span className="text-[9px] font-bold uppercase tracking-wider bg-emerald-500/15 text-emerald-300 px-1.5 py-0.5 rounded">Sponsor</span>
                             )}
                             {c.exhibitsNab && !c.isSponsor && (
-                              <span className="text-[9px] font-bold uppercase tracking-wider bg-amber-500/15 text-amber-300 px-1.5 py-0.5 rounded">NAB 26</span>
+                              <span className="text-[9px] font-bold uppercase tracking-wider bg-amber-500/15 text-amber-300 px-1.5 py-0.5 rounded">2026 NAB Show</span>
                             )}
                           </Link>
                         </li>