feat: load version.json at startup, expose via /api/health

server.js

@@ -29,8 +29,19 @@ function audit(action, entityType, entityId, performedBy, details) {
   }
 }
 
+// ── Version info (written by Dockerfile at build time) ───────────────────────
+// Falls back to { sha: 'dev' } when running outside a Docker build (local dev).
+let BUILD_VERSION = { sha: 'dev', shortSha: 'dev', buildTime: null };
+try {
+  BUILD_VERSION = require('./client/dist/version.json');
+} catch (_) { /* pre-build or local dev — stub values are fine */ }
+
 // Health
-app.get('/api/health', (req, res) => res.json({ status: 'ok', timestamp: new Date().toISOString() }));
+app.get('/api/health', (req, res) => res.json({
+  status:    'ok',
+  timestamp: new Date().toISOString(),
+  version:   BUILD_VERSION,
+}));
 
 // ── Employees ────────────────────────────────────────────────────────────────
 app.get('/api/employees', (req, res) => {