feat: add per-platform SEO landing pages (/youtube-downloader, etc.)

Create a dedicated, dynamically-routed page for each of 15 curated
platforms (YouTube, TikTok, Instagram, Facebook, X, Reddit, Pinterest,
Vimeo, SoundCloud, Twitch, Dailymotion, LinkedIn, Tumblr, VK, Snapchat)
under /[locale]/[slug], with a tailored hero, an example URL matched
to the platform, a unique "about" paragraph, and a mix of
platform-specific and shared FAQ items, all translated across
en/fr/es/it. Unknown slugs 404.

Kept the scope to a curated list rather than all 1380 yt-dlp
extractors to avoid thin/duplicate "doorway page" content that search
engines penalize.

The homepage's platform badges and the "+1000 sites" links now point
to these pages, extracted the FAQ accordion markup into a shared
FaqAccordion component reused by both the homepage FAQ and the new
platform pages.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/components/FaqAccordion.tsx

@@ -0,0 +1,39 @@
+import type { ReactNode } from 'react'
+
+function ChevronIcon() {
+  return (
+    <svg
+      width="18"
+      height="18"
+      viewBox="0 0 24 24"
+      fill="none"
+      stroke="currentColor"
+      strokeWidth="2"
+      strokeLinecap="round"
+      strokeLinejoin="round"
+      aria-hidden
+      className="shrink-0 transition-transform duration-200 group-open:rotate-180"
+    >
+      <path d="M6 9l6 6 6-6" />
+    </svg>
+  )
+}
+
+export function FaqAccordion({ items }: { items: { q: string; a: ReactNode }[] }) {
+  return (
+    <div className="space-y-3">
+      {items.map(({ q, a }) => (
+        <details
+          key={q}
+          className="group rounded-xl border border-gray-200 dark:border-slate-700 bg-white dark:bg-slate-900 px-5 py-4"
+        >
+          <summary className="flex items-center justify-between gap-4 cursor-pointer select-none font-medium text-gray-900 dark:text-gray-50 list-none [&::-webkit-details-marker]:hidden">
+            {q}
+            <ChevronIcon />
+          </summary>
+          <p className="mt-3 text-sm text-gray-500 dark:text-gray-400">{a}</p>
+        </details>
+      ))}
+    </div>
+  )
+}