feat(backend): add foundation services and sql idempotency

backend/command-api/src/routes/health.js

@@ -0,0 +1,12 @@
+import { Router } from 'express';
+
+export const healthRouter = Router();
+
+healthRouter.get('/healthz', (req, res) => {
+  res.status(200).json({
+    ok: true,
+    service: 'krow-command-api',
+    version: process.env.SERVICE_VERSION || 'dev',
+    requestId: req.requestId,
+  });
+});