P0-3/4/5: route error boundary, null guards, slug fallback, search

P0-3 (category page crash):
- Add src/app/error.tsx and src/app/global-error.tsx so any future render
  error shows a real ref id instead of the bare client-exception toast.
- NewsPageClient: null-guard every field accessed during search/category/
  sort filtering and article render (title, excerpt, author, tags,
  category, date, image, alt). The user-visible link
  /news?category=live-production now also hydrates filter state from
  ?category= and ?search= search-params, so the dropdown actually filters.

P0-4 (/articles/[slug] 404s):
- /articles/[slug] and /news/[slug]: on slug miss, redirect("/news")
  instead of notFound(). Dead links from the hardcoded NewsTicker /
  FeaturedBento / ArticleFeed arrays now land on the news index instead
  of dead-ending on 404.
- legacy-source: add searchLegacyArticles() (title/excerpt/author ilike).

P0-5 (header search):
- Header: wire Enter on the desktop and mobile search inputs and make
  both search icons clickable buttons. Submits to /search?q=<query>.
- New /search route: server component that runs searchLegacyArticles
  and renders results in the same card style as /news.

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

src/app/articles/[slug]/page.tsx

@@ -1,5 +1,5 @@
 import type { Metadata } from "next";
-import { notFound } from "next/navigation";
+import { redirect } from "next/navigation";
 import ArticleDetailPage from "./ArticleDetailClient";
 import type { Article } from "@/lib/articles/types";
 import {
@@ -66,7 +66,11 @@ export async function generateStaticParams() {
 export default async function ArticlePage({ params }: PageProps) {
   const { slug } = await params;
   const { article, related } = await loadArticle(slug);
-  if (!article) notFound();
+  if (!article) {
+    // Slug isn't in any of our article tables — send the reader to the news
+    // index so a click from the homepage/ticker doesn't dead-end on 404.
+    redirect("/news");
+  }
 
   const articleSchema = {
     "@context": "https://schema.org",