slice 1+2: header social URLs, drop TwitterX/Press Kit, wrap About/Team/PressKit, add /newsletter + /rss

- Header.tsx: bare linkedin/instagram/facebook URLs → /broadcastbeat handles; remove TwitterXIcon from social bar + import (Footer retains TwitterXIcon per "DO NOT OVERRIDE" marker)
- AboutDropdown.tsx: drop "Press kit" item (the page itself stays at /about/press-kit, just delisted from menu)
- SystemStatusBar.tsx: remove "Index online" pulse-dot and "N wire sources" span (keep articles count + events count + build version)
- /about, /about/team, /about/press-kit: wrap in Header+Footer (previously rendered bare <main>)
- /newsletter/page.tsx (new): redirect to /newsletter/archive — Header was 404'ing on /newsletter
- /rss/route.ts (new): dynamic RSS feed reading from legacy-source news section; replaces 404 at /rss

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

src/app/newsletter/page.tsx

@@ -0,0 +1,11 @@
+import { redirect } from "next/navigation";
+
+export const metadata = {
+  title: "Newsletter — BroadcastBeat",
+  description: "BroadcastBeat newsletter archive.",
+  alternates: { canonical: "/newsletter/archive" },
+};
+
+export default function NewsletterIndex() {
+  redirect("/newsletter/archive");
+}