Fix: add debounce to renderTasks to prevent frontend freeze during WebSocket updates

backend/static/app.js

@@ -7,6 +7,7 @@ class TranscriptionApp {
         this.ws = null;
         this.tasks = new Map();
         this.currentFile = null;
+        this.renderTimeout = null;
         this.init();
     }
 
@@ -170,6 +171,8 @@ class TranscriptionApp {
     }
 
     renderTasks() {
+        if (this.renderTimeout) clearTimeout(this.renderTimeout);
+        this.renderTimeout = setTimeout(() => {
             const container = document.getElementById('tasksList');
             const tasks = Array.from(this.tasks.values());
 
@@ -179,6 +182,7 @@ class TranscriptionApp {
             }
 
             container.innerHTML = tasks.map(task => this.renderTaskItem(task)).join('');
+        }, 100);
     }
 
     renderTaskItem(task) {