OG: fallback image + Railway API URL for Vercel WAF bypass

Vercel's "Security Checkpoint" (WAF) blocks automated requests to
/api/og/* — including Twitter's crawler. Added fallback og:image so
cards always show something even when the dynamic image is blocked.

User action needed: whitelist /api/og/* in Vercel Dashboard → Settings
→ Security to enable the dynamic card image.

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

Author: rushgamebase-dev

apps/web/app/markets/[address]/layout.tsx

@@ -63,6 +63,7 @@ export async function generateMetadata({
   const title = `${market.question} | Rush Markets`;
   const description = `${yesLabel} ${yesOdds}% vs ${noLabel} ${noOdds}%${pool ? ` · ${pool} pool` : ""}${timer !== "Ended" ? ` · ${timer}` : ""} — Bet now on Rush`;
   const ogImageUrl = `${SITE_URL}/api/og/${address}`;
+  const ogFallback = `${SITE_URL}/og-fallback.png`;
   const marketUrl = `${SITE_URL}/markets/${address}`;
 
   return {
@@ -73,14 +74,17 @@ export async function generateMetadata({
       description,
       url: marketUrl,
       siteName: "Rush Markets",
-      images: [{ url: ogImageUrl, width: 1200, height: 630, alt: market.question }],
+      images: [
+        { url: ogImageUrl, width: 1200, height: 630, alt: market.question },
+        { url: ogFallback, width: 1200, height: 630, alt: "Rush Markets" },
+      ],
       type: "website",
     },
     twitter: {
       card: "summary_large_image",
       title: market.question,
       description,
-      images: [ogImageUrl],
+      images: [ogImageUrl, ogFallback],
     },
   };
 }