feat: organizers, meetups UI, Plausible analytics, and migration tooling

- Add organizer model/API, admin and public organizer pages, meetup cards
- Refresh events/home/contact; add calendar dialog and carousel components
- Optional Plausible via NEXT_PUBLIC_PLAUSIBLE_* env vars in root layout
- Prisma migration, seed updates, baseline-and-migrate script

Made-with: Cursor

frontend/app/events/[id]/page.tsx

@@ -26,9 +26,10 @@ export async function generateMetadata({ params }: Props): Promise<Metadata> {
     return { title: "Event Not Found" };
   }
 
+  const orgLabel = event.organizer?.name || "Belgian Bitcoin Embassy";
   const description =
     event.description?.slice(0, 160) ||
-    `Bitcoin meetup: ${event.title}${event.location ? ` in ${event.location}` : ""}. Organized by the Belgian Bitcoin Embassy.`;
+    `Bitcoin meetup: ${event.title}${event.location ? ` in ${event.location}` : ""}. Organized by ${orgLabel}.`;
 
   const ogImage = event.imageId
     ? `/media/${event.imageId}`
@@ -69,6 +70,12 @@ export default async function EventDetailPage({ params }: Props) {
             location={event.location}
             url={`${siteUrl}/events/${id}`}
             imageUrl={event.imageId ? `${siteUrl}/media/${event.imageId}` : undefined}
+            organizerName={event.organizer?.name}
+            organizerUrl={
+              event.organizer?.slug
+                ? `${siteUrl}/events/organizer/${event.organizer.slug}`
+                : undefined
+            }
           />
           <BreadcrumbJsonLd
             items={[