aio-interface: show sub-steps for starting containers

Signed-off-by: Simon L. <szaimen@e.mail.de>

php/public/overlay-log.js

@@ -0,0 +1,27 @@
+document.addEventListener("DOMContentLoaded", function(event) {
+    function displayOverlayLogMessage(message) {
+        const overlayLogElement = document.getElementById('overlay-log');
+        if (!overlayLogElement) {
+            return;
+        }
+        overlayLogElement.textContent = message;
+    }
+
+    // Attempt to connect to Server-Sent Events at /events/containers and listen for 'container-start' events
+    if (typeof EventSource !== 'undefined') {
+        try {
+            const serverSentEventSource = new EventSource('events/containers');
+            serverSentEventSource.addEventListener('container-start', function(serverSentEvent) {
+                try {
+                    let parsedPayload = JSON.parse(serverSentEvent.data);
+                    displayOverlayLogMessage(parsedPayload.name || serverSentEvent.data);
+                } catch (parseError) {
+                    displayOverlayLogMessage(serverSentEvent.data);
+                }
+            });
+            serverSentEventSource.onerror = function() { serverSentEventSource.close(); };
+        } catch (connectionError) {
+            /* ignore if Server-Sent Events are not available */
+        }
+    }
+});