feat: user relay management, blog naddr sync, and OG image update

Add UserRelay API and dashboard relays tab with NIP-65 import, store post
naddr for Nostr articles, and ship Prisma migrations for board tables,
user relays, and post metadata.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/app/layout.tsx

@@ -23,7 +23,7 @@ export const metadata: Metadata = {
     template: "%s | Belgian Bitcoin Embassy",
   },
   description:
-    "Belgium's sovereign Bitcoin community. Monthly meetups in Antwerp, Bitcoin education, and curated Nostr content. No hype, just signal.",
+    "Discover Bitcoin meetups across Belgium. Real conversations, education, and a strong local community.",
   keywords: [
     "Bitcoin",
     "Belgium",
@@ -44,7 +44,7 @@ export const metadata: Metadata = {
     siteName: "Belgian Bitcoin Embassy",
     title: "Belgian Bitcoin Embassy | Bitcoin Meetups & Education in Belgium",
     description:
-      "Belgium's sovereign Bitcoin community. Monthly meetups, education, and curated Nostr content.",
+      "Discover Bitcoin meetups across Belgium. Real conversations, education, and a strong local community.",
     images: [
       {
         url: "/og-default.png",
@@ -58,7 +58,7 @@ export const metadata: Metadata = {
     card: "summary_large_image",
     title: "Belgian Bitcoin Embassy",
     description:
-      "Belgium's sovereign Bitcoin community. Monthly meetups, education, and curated Nostr content.",
+      "Discover Bitcoin meetups across Belgium. Real conversations, education, and a strong local community.",
     images: ["/og-default.png"],
   },
   robots: {