feat: add initial project configuration and smoke tests

- Created pnpm workspace configuration to manage packages.
- Added a placeholder .gitkeep file in the scripts directory.
- Implemented a smoke test script to validate core API and web endpoints.
- Established TypeScript base configuration for consistent compilation settings.
- Introduced Turbo configuration for task management and build processes.

packages/api/prisma/schema.prisma

@@ -0,0 +1,14 @@
+datasource db {
+  provider = "postgresql"
+}
+
+generator client {
+  provider     = "prisma-client"
+  output       = "../src/generated/prisma"
+  moduleFormat = "cjs"
+}
+
+// Placeholder model — removed when real models are added in feature plans
+model Placeholder {
+  id String @id @default(uuid())
+}

packages/api/prisma/seed.ts

@@ -0,0 +1,43 @@
+/**
+ * Prisma seed script — creates deterministic test data for local development.
+ *
+ * Run:  npx prisma db seed
+ *       make dev-seed
+ *
+ * This is idempotent — safe to run multiple times.
+ *
+ * Replace/extend with real seed data when feature models are added.
+ */
+import { PrismaClient } from '../src/generated/prisma/client';
+import { PrismaPg } from '@prisma/adapter-pg';
+
+const adapter = new PrismaPg({ connectionString: process.env['DATABASE_URL']! });
+const prisma = new PrismaClient({ adapter });
+
+async function main(): Promise<void> {
+  console.log('');
+  console.log('🌱 Seeding davinci-platform dev database...');
+  console.log('');
+
+  // Placeholder — replace when real models exist
+  const existing = await prisma.placeholder.findFirst();
+  if (existing) {
+    console.log('  ⏭  Placeholder record already exists');
+  } else {
+    await prisma.placeholder.create({ data: {} });
+    console.log('  ✅ Placeholder record created');
+  }
+
+  console.log('');
+  console.log('✅ Seed complete');
+  console.log('');
+}
+
+main()
+  .catch((e) => {
+    console.error('❌ Seed failed:', e);
+    process.exit(1);
+  })
+  .finally(async () => {
+    await prisma.$disconnect();
+  });