fix: prisma connection exhaustion & firebase lazy init

- prisma/schema.prisma: tambah binaryTargets debian & linux-musl untuk Docker
- src/lib/prisma.ts: pakai global singleton di dev & prod, hapus eager $connect()
- src/lib/firebase-admin.ts: lazy initialization agar tidak crash saat build time
- .env.example: lengkap dengan semua env variable + connection_limit & pool_timeout

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

src/lib/firebase-admin.ts

@@ -1,24 +1,25 @@
 // lib/firebase-admin.ts
 import { cert, getApp, getApps, initializeApp } from 'firebase-admin/app';
-import { getMessaging } from 'firebase-admin/messaging';
+import { getMessaging, Messaging } from 'firebase-admin/messaging';
 
-// Ambil dari environment
-const serviceAccount = {
-  projectId: process.env.FIREBASE_ADMIN_PROJECT_ID,
-  clientEmail: process.env.FIREBASE_ADMIN_CLIENT_EMAIL,
-  privateKey: process.env.FIREBASE_ADMIN_PRIVATE_KEY?.replace(/\\n/g, '\n'),
-};
+function getAdminApp() {
+  if (getApps().length > 0) return getApp();
 
-if (!serviceAccount.projectId || !serviceAccount.clientEmail || !serviceAccount.privateKey) {
-  throw new Error('Firebase Admin credentials are missing in environment variables');
+  const privateKey = process.env.FIREBASE_ADMIN_PRIVATE_KEY?.replace(/\\n/g, '\n');
+  const projectId = process.env.FIREBASE_ADMIN_PROJECT_ID;
+  const clientEmail = process.env.FIREBASE_ADMIN_CLIENT_EMAIL;
+
+  if (!projectId || !clientEmail || !privateKey) {
+    throw new Error('Firebase Admin credentials are missing in environment variables');
+  }
+
+  return initializeApp({
+    credential: cert({ projectId, clientEmail, privateKey }),
+    projectId,
+  });
 }
 
-// Inisialisasi hanya sekali
-const app = !getApps().length
-  ? initializeApp({
-      credential: cert(serviceAccount),
-      projectId: serviceAccount.projectId,
-    })
-  : getApp();
-
-export const adminMessaging = getMessaging(app);
+export const adminMessaging: Pick<Messaging, 'send' | 'sendEachForMulticast'> = {
+  send: (message) => getMessaging(getAdminApp()).send(message),
+  sendEachForMulticast: (message) => getMessaging(getAdminApp()).sendEachForMulticast(message),
+};