fix: Replace SSE with polling for WebSocket status to prevent connection pool exhaustion

- Replace persistent SSE connections with lightweight polling (10s interval)
- Optimize WebSocket status fetching using bulk endpoint instead of N individual calls
- Fix N+1 query problem in /dashboard/hosts endpoint (39 queries → 4 queries)
- Increase database connection pool limit from 5 to 50 via environment variables
- Increase Axios timeout from 10s to 30s for complex operations
- Fix malformed WebSocket routes causing 404 on bulk status endpoint

Fixes timeout issues when adding hosts with multiple WebSocket agents connected.
Reduces database connections from 19 persistent SSE + retries to 1 poll every 10 seconds.

backend/src/routes/wsRoutes.js

@@ -11,7 +11,31 @@ const {
 
 const router = express.Router();
 
-// Get WebSocket connection status by api_id (no database access - pure memory lookup)
+// Get WebSocket connection status for multiple hosts at once (bulk endpoint)
+router.get("/status", authenticateToken, async (req, res) => {
+	try {
+		const { apiIds } = req.query; // Comma-separated list of api_ids
+		const idArray = apiIds ? apiIds.split(",").filter((id) => id.trim()) : [];
+
+		const statusMap = {};
+		idArray.forEach((apiId) => {
+			statusMap[apiId] = getConnectionInfo(apiId);
+		});
+
+		res.json({
+			success: true,
+			data: statusMap,
+		});
+	} catch (error) {
+		console.error("Error fetching bulk WebSocket status:", error);
+		res.status(500).json({
+			success: false,
+			error: "Failed to fetch WebSocket status",
+		});
+	}
+});
+
+// Get WebSocket connection status by api_id (single endpoint)
 router.get("/status/:apiId", authenticateToken, async (req, res) => {
 	try {
 		const { apiId } = req.params;