fix: Docker multi-stage build for sqlite3, health endpoint, productValidator exports

- Dockerfile: multi-stage build (builder with python3+g++ for native addons)
- Dockerfile: wireguard-tools from edge/community repo
- Dockerfile: removed USER appuser (start.sh needs root for wg-quick)
- Dockerfile: health check on port 3000
- Added /health HTTP endpoint in index.js for Docker healthcheck
- Fixed productValidator.js: added named exports (validateProductName, validateProductPrice)
- Added better-sqlite3 as fallback dependency

src/index.js

@@ -70,3 +70,18 @@ process.on('unhandledRejection', (error) => {
 });
 
 logger.info('Bot is running...');
+
+// Health check endpoint for Docker
+import http from 'http';
+const healthServer = http.createServer((req, res) => {
+    if (req.url === '/health') {
+        res.writeHead(200, { 'Content-Type': 'application/json' });
+        res.end(JSON.stringify({ status: 'ok', uptime: process.uptime() }));
+    } else {
+        res.writeHead(404);
+        res.end('Not found');
+    }
+});
+healthServer.listen(3000, () => {
+    logger.info({ port: 3000 }, 'Health check server started');
+});