feat: add health check route

Implement handleHealth endpoint for Bun.serve to verify DB connection.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/routes/health.js

@@ -0,0 +1,13 @@
+import logger from '../utils/logger.js';
+import { db } from '../db/index.js';
+import { sql } from 'drizzle-orm';
+
+export const handleHealth = async (req) => {
+  try {
+    await db.execute(sql`SELECT 1`);
+    return Response.json({ status: 'ok' }, { status: 200 });
+  } catch (error) {
+    logger.error('Health check failed', { error: error.message });
+    return Response.json({ status: 'error', error: error.message }, { status: 500 });
+  }
+};