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>

.env.example

@@ -0,0 +1,53 @@
+# ==============================
+# Database
+# ==============================
+# Tambahkan connection_limit dan pool_timeout untuk mencegah connection exhaustion
+DATABASE_URL="postgresql://user:password@localhost:5432/dbname?connection_limit=10&pool_timeout=20"
+
+# ==============================
+# Auth / Session
+# ==============================
+WIBU_PWD="your_wibu_password"
+NEXT_PUBLIC_BASE_TOKEN_KEY="your_token_key"
+NEXT_PUBLIC_BASE_SESSION_KEY="your_session_key"
+
+# ==============================
+# Payment Gateway (Midtrans)
+# ==============================
+Client_KEY="your_midtrans_client_key"
+Server_KEY="your_midtrans_server_key"
+
+# ==============================
+# Maps
+# ==============================
+MAPBOX_TOKEN="your_mapbox_token"
+
+# ==============================
+# Realtime (WebSocket)
+# ==============================
+WS_APIKEY="your_ws_api_key"
+NEXT_PUBLIC_WIBU_REALTIME_TOKEN="your_realtime_token"
+
+# ==============================
+# Email (Resend)
+# ==============================
+RESEND_APIKEY="your_resend_api_key"
+
+# ==============================
+# WhatsApp
+# ==============================
+WA_SERVER_TOKEN="your_wa_server_token"
+
+# ==============================
+# Firebase Admin (Push Notification)
+# ==============================
+FIREBASE_ADMIN_PROJECT_ID="your_firebase_project_id"
+FIREBASE_ADMIN_CLIENT_EMAIL="your_firebase_client_email@project.iam.gserviceaccount.com"
+# Private key: salin dari service account JSON, ganti newline dengan \n
+FIREBASE_ADMIN_PRIVATE_KEY="-----BEGIN PRIVATE KEY-----\nYOUR_PRIVATE_KEY_HERE\n-----END PRIVATE KEY-----\n"
+
+# ==============================
+# App
+# ==============================
+NEXT_PUBLIC_API_URL="http://localhost:3000"
+LOG_LEVEL="info"