feat: add User Prisma model + migration

prisma/migrations/20260731044659_add_user/migration.sql

@@ -0,0 +1,13 @@
+-- CreateTable
+CREATE TABLE "users" (
+    "id" UUID NOT NULL,
+    "email" TEXT NOT NULL,
+    "password_hash" TEXT NOT NULL,
+    "name" TEXT NOT NULL,
+    "created_at" TIMESTAMPTZ(6) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+
+    CONSTRAINT "users_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateIndex
+CREATE UNIQUE INDEX "users_email_key" ON "users"("email");