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/components/public/JsonLd.tsx

@@ -106,6 +106,8 @@ interface EventJsonLdProps {
   location?: string;
   url: string;
   imageUrl?: string;
+  organizerName?: string;
+  organizerUrl?: string;
 }
 
 export function EventJsonLd({
@@ -115,7 +117,11 @@ export function EventJsonLd({
   location,
   url,
   imageUrl,
+  organizerName,
+  organizerUrl,
 }: EventJsonLdProps) {
+  const orgName = organizerName || "Belgian Bitcoin Embassy";
+  const orgUrl = organizerUrl || siteUrl;
   return (
     <JsonLd
       data={{
@@ -141,8 +147,8 @@ export function EventJsonLd({
           : {}),
         organizer: {
           "@type": "Organization",
-          name: "Belgian Bitcoin Embassy",
-          url: siteUrl,
+          name: orgName,
+          url: orgUrl,
         },
         image:
           imageUrl || `${siteUrl}/og?title=${encodeURIComponent(name)}&type=event`,