feat: infra 패키지 추가 및 PostgreSQL, Redis 커넥터 구현

packages/infra/prisma/schema.prisma

@@ -0,0 +1,10 @@
+generator client {
+    provider = "prisma-client-js"
+}
+
+datasource db {
+    provider = "postgresql"
+    url      = env("DATABASE_URL")
+}
+
+// TODO: Translate docs/architecture/postgres-schema.md into Prisma models.