homepage: remove top bar + fix subscribe + Staff Editorial header

1. Remove SystemStatusBar from root layout. The "29,220 articles
   indexed / 13 events tracked / [v2.0.0]" strip ate vertical space
   above the fold without serving readers.

2. /api/newsletter/subscribe was returning 500 "Failed to save
   subscription" because:
   - The route used the anon-session client and tried to UPSERT on
     bb.newsletter_subscribers, but the table's RLS only has an
     INSERT policy for the public role. Upsert needs INSERT+UPDATE,
     so the second branch failed RLS.
   - Switched to createAdminClient (service-role) — bypasses RLS,
     which is fine because this is a server-side endpoint with
     server-side email validation.
   - Welcome email now sends via nodemailer in a non-blocking
     background task so a slow SMTP doesn't hold up the response.
     Newer HTML template, brand-aligned, with a real CTA back to
     /news.

   Side work to wire SMTP (done out-of-band):
   - Created newsletter@broadcastbeat.com mailbox in Mailcow via
     the API (2GB quota, active, no force-pw-update).
   - Set SMTP_HOST=mail.onsethost.com, SMTP_PORT=587,
     SMTP_USER/PASS/FROM_EMAIL/FROM_NAME in Coolify env so the
     welcome email actually fires after the next deploy.

3. FeaturedBentoFromDb section header: "Featured · staff editorial"
   (small mono caps) → "Staff Editorial" (font-serif 2xl/3xl, bold,
   with a thin metadata line "Selected by our newsroom" beside it
   and a 2px bottom rule). Matches the editorial typography on the
   article pages.

src/components/FeaturedBentoFromDb.tsx

@@ -60,13 +60,16 @@ export default async function FeaturedBento() {
 
   return (
     <section className="max-w-container mx-auto px-4 my-8" aria-label="Featured stories">
-      <div className="flex items-center gap-3 mb-3 flex-wrap">
-        <h2 className="font-mono text-xs uppercase tracking-wider text-[#6b7280] whitespace-nowrap">
-          Featured · staff editorial
+      <div className="flex items-end gap-4 mb-4 flex-wrap pb-2 border-b-2 border-[#2a2a2a]">
+        <h2 className="font-serif text-2xl md:text-3xl font-bold tracking-tight text-white whitespace-nowrap leading-none">
+          Staff Editorial
         </h2>
-        <div className="flex-1 h-px bg-[#2a2a2a]" />
-        <Link href="/news?category=Featured" className="text-[11px] font-mono text-[var(--color-text-info,#60a5fa)] hover:underline whitespace-nowrap">
-          All featured →
+        <span className="font-mono text-[10px] uppercase tracking-[0.2em] text-[#6b7280] pb-1">
+          Selected by our newsroom
+        </span>
+        <div className="flex-1" />
+        <Link href="/news?category=Featured" className="text-[11px] font-mono text-[var(--color-text-info,#60a5fa)] hover:underline whitespace-nowrap pb-1">
+          See all →
         </Link>
       </div>