feat: introduce backend url environment variable

ref: N25B-352

src/pages/MonitoringPage/MonitoringPageComponents.tsx

@@ -4,6 +4,7 @@
 import React, { useEffect, useState } from 'react';
 import styles from './MonitoringPage.module.css';
 import { sendAPICall } from './MonitoringPageAPI';
+import { API_BASE_URL } from '../../config/api.ts';
 
 // --- GESTURE COMPONENT ---
 export const GestureControls: React.FC = () => {
@@ -201,7 +202,7 @@ export const RobotConnected = () => {
     useEffect(() => {
       // Open a Server-Sent Events (SSE) connection to receive live ping updates.
       // We're expecting a stream of data like that looks like this: `data = False` or `data = True`
-      const eventSource = new EventSource("http://localhost:8000/robot/ping_stream");
+      const eventSource = new EventSource(`${API_BASE_URL}/robot/ping_stream`);
       eventSource.onmessage = (event) => {
       
         // Expecting messages in JSON format: `true` or `false`
@@ -232,4 +233,4 @@ export const RobotConnected = () => {
     <p className={connected ? styles.connected : styles.disconnected }>{connected ? "● Robot is connected" : "● Robot is disconnected"}</p>
   </div>
   )
-}
+}