ads: float SidebarAdStack at top of <main> on 7 more pages

gear, technology, search, reading-list, show-coverage, authors/[slug],
forum/thread/[id] all now render the 300x600 + 300x250 stack as a
floating right column at the top of the content area. Existing
single-column page structure preserved (content wraps).

Maximizes impression count: every pageview across these pages now
counts 300x600 + every 300x250 in the stack, on top of the existing
728x90 in Header.

src/app/show-coverage/page.tsx

@@ -4,6 +4,7 @@ import Header from "@/components/Header";
 import Footer from "@/components/Footer";
 import AdImage from "@/components/AdImage";
 import { ADS_728X90, shuffle } from "@/lib/ads";
+import SidebarAdStack from "@/components/SidebarAdStack";
 
 export const dynamic = "force-dynamic";
 export const revalidate = 600;
@@ -69,6 +70,7 @@ export default async function ShowCoverageIndex() {
     <div className="min-h-screen bg-background">
       <Header />
       <main className="mx-auto max-w-6xl px-6 py-10 text-[#e5e7eb]">
+      <aside className="float-right ml-6 mb-6 hidden lg:block max-w-[300px]"><SidebarAdStack /></aside>
         <header className="mb-8">
           <h1 className="font-serif text-4xl font-bold tracking-tight">Industry Show Coverage</h1>
           <p className="text-sm text-[#9ca3af] mt-2 font-mono">