feat(bf): put the HOST27 deal on the homepage; deal window now starts 2 November

The coupon applies today (signed-out test: post_basket -> /coupon/HOST27 ->
cart 295.00 from a 395.00 list), so the offer starts today, not on 16 November.

- index.html: one seasonal banner above the hero, a single <a> to
  /odoo-black-friday/. Homepage components and CI only (midnight/brass/cream,
  Marcellus/Inter). No script, no tracking tag, no event: the homepage has no
  consent gate, so nothing measurable may be added there. Hero, server
  selector, section order and JSON-LD untouched. Dated for removal after
  30 November 2026.
- odoo-black-friday/: every start claim 16 -> 2 (meta, og:image:alt, JSON-LD
  WebPage description + two FAQ answers, hero-sub, two body FAQ answers).
  End date, countdown instant, forms, consent gate and the three conversions
  unchanged.
- odoo-hosting-offers/: same start claim on the second ad lander, so the AG1
  visitor is not told the deal begins in two weeks.

Every price claim keeps the "first year" qualifier.

index.html

@@ -219,6 +219,16 @@
       #customQuoteModal .biz-success h3{color:var(--midnight)}
       #customQuoteModal .biz-success p{color:var(--midnight)}
       @media(max-width:600px){.oca-table td,.oca-table th{padding:.5rem .65rem;font-size:.8rem}.ow-panel{left:5%;right:5%}.ow-close{top:.5rem;right:.5rem;font-size:1.6rem}}
+      /* Black Friday 2026 — seasonal top banner. Live 2-30 November 2026 only: remove this rule
+         together with the .bf-topbar markup block at the top of <body> after 30 November 2026.
+         CI: midnight canvas, brass label/code/CTA only, cream-white body text. No script, no tag. */
+      .bf-topbar{display:flex;align-items:center;justify-content:center;gap:.3rem 1rem;flex-wrap:wrap;background:var(--midnight);border-bottom:1px solid var(--line-brass);padding:.65rem 1.25rem;font-family:Inter,sans-serif;font-size:.82rem;line-height:1.5;color:rgba(255,255,255,.82);text-align:center;text-decoration:none}
+      .bf-topbar:hover,.bf-topbar:focus-visible{background:var(--midnight-2);color:#fff}
+      .bf-topbar-badge{font-family:Marcellus,Georgia,serif;font-size:.78rem;letter-spacing:.08em;text-transform:uppercase;color:var(--brass);white-space:nowrap}
+      .bf-topbar strong{color:#fff;font-weight:600}
+      .bf-topbar-code{font-family:Marcellus,Georgia,serif;letter-spacing:.06em;color:var(--brass-bright)}
+      .bf-topbar-cta{color:var(--brass);white-space:nowrap}
+      .bf-topbar:hover .bf-topbar-cta,.bf-topbar:focus-visible .bf-topbar-cta{color:var(--brass-bright)}
     </style>
     <link rel="stylesheet" href="style.css" media="print" onload="this.media='all'" />
     <noscript><link rel="stylesheet" href="style.css" /></noscript>
@@ -239,6 +249,16 @@
     FORM: The Grand Hotel Business Lounge (model-pick, user-chosen). Seed key: 7db4dced.
     FINISH: unreviewed and undocumented is unfinished; this build ends with the finish review, the verdict, and DESIGN.md.
     -->
+    <!-- Black Friday 2026 — seasonal banner. Live 2-30 November 2026 only: remove this whole block
+         (and the .bf-topbar rules in <style>) after 30 November 2026. It is one link to the deal page:
+         no script, no tracking tag, no event. The offer itself lives on /odoo-black-friday/ only. -->
+    <a class="bf-topbar" href="/odoo-black-friday/">
+      <span class="bf-topbar-badge">Black Friday</span>
+      <span><strong>$100 off your first year</strong> &middot; On the Rise: $395 a year list &rarr; $295 for your first year</span>
+      <span>Code <span class="bf-topbar-code">HOST27</span> &middot; Ends 30 November 2026</span>
+      <span class="bf-topbar-cta">See the offer &rarr;</span>
+    </a>
+
     <!-- Hero -->
     <section class="hero">
       <div class="hero-notice" id="heroConfirmNotice" role="status" aria-live="polite" hidden>