feat: establish backend foundation

src/prisma/prisma.module.ts

@@ -0,0 +1,9 @@
+import { Global, Module } from '@nestjs/common';
+import { PrismaService } from './prisma.service';
+
+@Global()
+@Module({
+  providers: [PrismaService],
+  exports: [PrismaService],
+})
+export class PrismaModule {}

src/prisma/prisma.service.ts

@@ -0,0 +1,31 @@
+import { Injectable, OnModuleDestroy, OnModuleInit } from '@nestjs/common';
+import { ConfigService } from '@nestjs/config';
+import { PrismaBetterSqlite3 } from '@prisma/adapter-better-sqlite3';
+import { PrismaClient } from '../../generated/prisma/client';
+import { Environment } from '../config/env.validation';
+
+function getDatabaseUrl(config: ConfigService<Environment, true>): string {
+  return config.getOrThrow<string>('DATABASE_URL');
+}
+
+@Injectable()
+export class PrismaService
+  extends PrismaClient
+  implements OnModuleInit, OnModuleDestroy
+{
+  constructor(config: ConfigService<Environment, true>) {
+    super({
+      adapter: new PrismaBetterSqlite3({
+        url: getDatabaseUrl(config),
+      }),
+    });
+  }
+
+  onModuleInit(): Promise<void> {
+    return this.$connect();
+  }
+
+  onModuleDestroy(): Promise<void> {
+    return this.$disconnect();
+  }
+}