Disable syncing after several attempts

Refactor syncplay manager
Attempt fixing Safari issues (timeupdate event not firing)

src/workers/syncplay/syncplay.worker.js

@@ -0,0 +1,90 @@
+var SyncTimeThreshold = 2000; // milliseconds, overwritten by startSyncWatcher
+var SyncWatcherInterval = 1000; // milliseconds, overwritten by startSyncWatcher
+var lastSyncTime = new Date(); // internal state
+var syncWatcher; // holds value from setInterval
+
+/**
+ * Sends a message to the UI worker.
+ * @param {string} type 
+ * @param {*} data 
+ */
+function sendMessage (type, data) {
+    postMessage({
+        type: type,
+        data: data
+    });
+
+}
+
+/**
+ * Updates the state.
+ * @param {Date} syncTime The new state.
+ */
+function updateLastSyncTime (syncTime) {
+    lastSyncTime = syncTime;
+}
+
+/**
+ * Starts sync watcher.
+ * @param {Object} options Additional options to configure the watcher, like _interval_ and _threshold_.
+ */
+function startSyncWatcher(options) {
+    stopSyncWatcher();
+    if (options) {
+        if (options.interval) {
+            SyncWatcherInterval = options.interval;
+        }
+        if (options.threshold) {
+            SyncTimeThreshold = options.threshold;
+        }
+    }
+    syncWatcher = setInterval(syncWatcherCallback, SyncWatcherInterval);
+}
+
+/**
+ * Stops sync watcher.
+ */
+function stopSyncWatcher () {
+    if (syncWatcher) {
+        clearInterval(syncWatcher);
+        syncWatcher = null;
+    }
+}
+
+/**
+ * Oversees playback sync and makes sure that it gets called regularly.
+ */
+function syncWatcherCallback () {
+    const currentTime = new Date();
+    const elapsed = currentTime - lastSyncTime;
+    if (elapsed > SyncTimeThreshold) {
+        sendMessage("TriggerSync");
+    }
+}
+
+/**
+ * Handles messages from UI worker.
+ * @param {MessageEvent} event The message to handle.
+ */
+function handleMessage (event) {
+    const message = event.data;
+    switch (message.type) {
+        case "UpdateLastSyncTime":
+            updateLastSyncTime(message.data);
+            break;
+        case "StartSyncWatcher":
+            startSyncWatcher(message.data);
+            break;
+        case "StopSyncWatcher":
+            stopSyncWatcher();
+            break;
+        default:
+            console.error("Unknown message type:", message.type);
+            break;
+    }
+}
+
+// Listen for messages
+addEventListener("message", function (event) {
+    handleMessage(event);
+});