feat: initial NFC Attendance Hub implementation

- Multi-tenant client management with unique API keys
- Semaphore SMS integration (per-client key + sender name + credit balance)
- DB-based SMS queue with 3-attempt retry and exponential backoff
- Failed SMS dashboard with manual retry button
- Reports page with date/client filter and CSV export
- Admin auth via NextAuth (email/password)
- Docker Compose setup (app + PostgreSQL 16)
- Prisma 5 schema with SmsQueue, SmsLog, Client, User models

Tech: Next.js 14 App Router + TypeScript + Tailwind CSS + Prisma + PostgreSQL

lib/prisma.ts

@@ -0,0 +1,15 @@
+import { PrismaClient } from '@prisma/client'
+
+const globalForPrisma = globalThis as unknown as {
+  prisma: PrismaClient | undefined
+}
+
+export const prisma =
+  globalForPrisma.prisma ??
+  new PrismaClient({
+    log: process.env.NODE_ENV === 'development' ? ['query', 'error', 'warn'] : ['error'],
+  })
+
+if (process.env.NODE_ENV !== 'production') globalForPrisma.prisma = prisma
+
+export default prisma