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/lib/api.ts

@@ -51,10 +51,11 @@ export const api = {
     request<void>(`/posts/${id}`, { method: "DELETE" }),
 
   // Meetups
-  getMeetups: (params?: { status?: string; admin?: boolean }) => {
+  getMeetups: (params?: { status?: string; admin?: boolean; organizerSlug?: string }) => {
     const searchParams = new URLSearchParams();
     if (params?.status) searchParams.set("status", params.status);
     if (params?.admin) searchParams.set("admin", "true");
+    if (params?.organizerSlug) searchParams.set("organizerSlug", params.organizerSlug);
     const qs = searchParams.toString();
     return request<any[]>(`/meetups${qs ? `?${qs}` : ""}`);
   },
@@ -103,6 +104,17 @@ export const api = {
   deleteCategory: (id: string) =>
     request<void>(`/categories/${id}`, { method: "DELETE" }),
 
+  // Organizers
+  getOrganizers: () => request<any[]>("/organizers"),
+  getOrganizerBySlug: (slug: string) =>
+    request<any>(`/organizers/by-slug/${encodeURIComponent(slug)}`),
+  createOrganizer: (data: { name: string; slug: string }) =>
+    request<any>("/organizers", { method: "POST", body: JSON.stringify(data) }),
+  updateOrganizer: (id: string, data: { name?: string; slug?: string }) =>
+    request<any>(`/organizers/${id}`, { method: "PATCH", body: JSON.stringify(data) }),
+  deleteOrganizer: (id: string) =>
+    request<void>(`/organizers/${id}`, { method: "DELETE" }),
+
   // Relays
   getRelays: () => request<any[]>("/relays"),
   addRelay: (data: { url: string; priority?: number }) =>