feat(seo): set the Black Friday share image on the two BF pages

/odoo-black-friday/ gains og:image + og:image:width/height/alt + twitter:image
pointing at the 1200x630 OG card; /odoo-hosting-offers/ reuses the same card.
Both pages declared no og:image before.

odoo-hosting-offers/index.html

@@ -16,7 +16,15 @@
     />
     <meta property="og:type" content="website" />
     <meta property="og:url" content="https://odoo4projects.com/odoo-hosting-offers/" />
+    <meta property="og:image" content="https://odoo4projects.com/images/black-friday/bf2026-hosting-og.png" />
+    <meta property="og:image:width" content="1200" />
+    <meta property="og:image:height" content="630" />
+    <meta
+      property="og:image:alt"
+      content="Black Friday 2026 poster: 'Black Friday — 16–30 November', 'Save $100 on Odoo hosting' with a secret deal on the Bootcamp, and the code HOST27."
+    />
     <meta name="twitter:card" content="summary_large_image" />
+    <meta name="twitter:image" content="https://odoo4projects.com/images/black-friday/bf2026-hosting-og.png" />
     <link rel="icon" href="/images/favicon.ico" />
     <link rel="preconnect" href="https://fonts.googleapis.com" />
     <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin />