feat: add Express API base structure

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/api/src/config/env.ts

@@ -0,0 +1,20 @@
+import { z } from 'zod';
+
+const envSchema = z.object({
+  NODE_ENV: z.enum(['development', 'production', 'test']).default('development'),
+  PORT: z.string().default('4000'),
+  DATABASE_URL: z.string(),
+  JWT_SECRET: z.string().min(32),
+  JWT_EXPIRES_IN: z.string().default('15m'),
+  JWT_REFRESH_EXPIRES_IN: z.string().default('7d'),
+  CORS_ORIGIN: z.string().default('http://localhost:3000'),
+});
+
+const parsed = envSchema.safeParse(process.env);
+
+if (!parsed.success) {
+  console.error('❌ Invalid environment variables:', parsed.error.flatten().fieldErrors);
+  process.exit(1);
+}
+
+export const env = parsed.data;