feat: add Express API base structure

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

apps/api/src/app.ts

@@ -0,0 +1,31 @@
+import express from 'express';
+import cors from 'cors';
+import helmet from 'helmet';
+import { env } from './config/env.js';
+import { errorMiddleware } from './middlewares/error.middleware.js';
+
+const app = express();
+
+// Security
+app.use(helmet());
+app.use(cors({
+  origin: env.CORS_ORIGIN,
+  credentials: true,
+}));
+
+// Body parsing
+app.use(express.json());
+app.use(express.urlencoded({ extended: true }));
+
+// Health check
+app.get('/health', (req, res) => {
+  res.json({ status: 'ok', timestamp: new Date().toISOString() });
+});
+
+// API Routes (to be added)
+// app.use('/api/auth', authRoutes);
+
+// Error handling
+app.use(errorMiddleware);
+
+export { app };