feat: Snippets "The Lab" — category filters, search, language badges, code preview, modal keyboard nav (#72)

* fix: pass locale explicitly to Hero and force-dynamic on locale-sensitive API routes

- Hero.tsx: pass locale prop directly to getTranslations instead of
  relying on setRequestLocale async storage, which can be lost during
  Next.js RSC streaming
- book-reviews route: replace revalidate=300 with force-dynamic to
  prevent cached English responses being served to German locale requests
- content/page route: add runtime=nodejs and force-dynamic (was missing
  both, violating CLAUDE.md API route conventions)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* fix: scroll to top on locale switch and remove dashes from hero text

- HeaderClient: track locale prop changes with useRef and call
  window.scrollTo on switch to reliably reset scroll position
- messages/en.json + de.json: replace em dash with comma and remove
  hyphens from Self-Hoster/Full-Stack in hero description

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* Initial plan

* feat: improve Snippets/The Lab UI with category filters, search, language badges and code preview

Agent-Logs-Url: https://github.com/denshooter/portfolio/sessions/4a562022-cad7-4b4f-8bc4-1be022ecbf1e

Co-authored-by: denshooter <44590296+denshooter@users.noreply.github.com>

---------

Co-authored-by: denshooter <dennis@konkol.net>
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: denshooter <44590296+denshooter@users.noreply.github.com>

app/components/HeaderClient.tsx

@@ -1,6 +1,6 @@
 "use client";
 
-import { useState, useEffect } from "react";
+import { useState, useEffect, useRef } from "react";
 import { SiGithub, SiLinkedin } from "react-icons/si";
 import Link from "next/link";
 import { usePathname, useSearchParams } from "next/navigation";
@@ -27,6 +27,14 @@ export default function HeaderClient({ locale, translations }: HeaderClientProps
   const [scrolled, setScrolled] = useState(false);
   const pathname = usePathname();
   const searchParams = useSearchParams();
+  const prevLocale = useRef(locale);
+
+  useEffect(() => {
+    if (prevLocale.current !== locale) {
+      window.scrollTo({ top: 0, behavior: "instant" });
+      prevLocale.current = locale;
+    }
+  }, [locale]);
 
   const isHome = pathname === `/${locale}` || pathname === `/${locale}/`;