feat(desa): Kalender Event Budaya — fitur admin/public, seeder, pagination, fix duplicate options

- Tambah fitur Kalender Event Budaya di admin CMS (list, detail, edit, hapus)
- Tambah state Valtio (create, findMany, findUnique, edit, delete, findUpcoming)
- Tambah endpoint API /find-upcoming untuk event mendatang
- Tambah halaman public /darmasaba/desa/event-budaya dengan pagination 5 data/halaman
- Switch public page dari findUpcoming ke findMany agar pagination berjalan
- Tambah menu "Kalender Event Budaya" di navbar (id: 2.9)
- Perluas seeder event budaya: 8 → 34 events mencakup 2025-2026
- Fix: deduplikasi kategoriOptions di kegiatan-desa public page (Mantine Select error)
- Hapus STRUKTUR.md yang sudah tidak relevan

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/api/[[...slugs]]/_lib/desa/event-budaya/find-upcoming.ts

@@ -0,0 +1,24 @@
+import prisma from "@/lib/prisma";
+
+async function eventBudayaFindUpcoming() {
+  const today = new Date();
+  today.setHours(0, 0, 0, 0);
+
+  try {
+    const data = await prisma.eventBudaya.findMany({
+      where: {
+        isActive: true,
+        tanggal: { gte: today },
+      },
+      orderBy: { tanggal: "asc" },
+      take: 20,
+    });
+
+    return { success: true, data };
+  } catch (e) {
+    console.error("Error di eventBudayaFindUpcoming:", e);
+    return { success: false, message: "Gagal mengambil event mendatang" };
+  }
+}
+
+export default eventBudayaFindUpcoming;

src/app/api/[[...slugs]]/_lib/desa/event-budaya/index.ts

@@ -1,5 +1,6 @@
 import Elysia, { t } from "elysia";
 import eventBudayaFindMany from "./find-many";
+import eventBudayaFindUpcoming from "./find-upcoming";
 import eventBudayaFindUnique from "./findUnique";
 import eventBudayaCreate from "./create";
 import eventBudayaDelete from "./del";
@@ -7,6 +8,7 @@ import eventBudayaUpdate from "./updt";
 
 const EventBudaya = new Elysia({ prefix: "/eventbudaya", tags: ["Desa/Event Budaya"] })
   .get("/find-many", eventBudayaFindMany)
+  .get("/find-upcoming", eventBudayaFindUpcoming)
   .get("/:id", eventBudayaFindUnique)
   .post("/create", eventBudayaCreate, {
     body: t.Object({