feat(client): start to use a better eventemitter

.gitignore

@@ -9,3 +9,4 @@ readur_uploads/
 readur_watch/
 test-results/
 uploads/
+.claude/settings.local.json

frontend/package-lock.json

@@ -18,6 +18,7 @@
         "@types/uuid": "^10.0.0",
         "axios": "^1.3.0",
         "date-fns": "^4.1.0",
+        "eventemitter3": "^5.0.1",
         "react": "^19.0.0",
         "react-dom": "^19.0.0",
         "react-dropzone": "^14.2.3",
@@ -2785,6 +2786,12 @@
         "url": "https://github.com/sponsors/sindresorhus"
       }
     },
+    "node_modules/eventemitter3": {
+      "version": "5.0.1",
+      "resolved": "https://registry.npmjs.org/eventemitter3/-/eventemitter3-5.0.1.tgz",
+      "integrity": "sha512-GWkBvjiSZK87ELrYOSESUYeVIc9mvLLf/nXalMOS5dYrgZq9o5OVkbZAVM06CVxYsCwH9BDZFPlQTlPA1j4ahA==",
+      "license": "MIT"
+    },
     "node_modules/fdir": {
       "version": "6.4.6",
       "resolved": "https://registry.npmjs.org/fdir/-/fdir-6.4.6.tgz",

frontend/package.json

@@ -29,6 +29,7 @@
     "@types/uuid": "^10.0.0",
     "axios": "^1.3.0",
     "date-fns": "^4.1.0",
+    "eventemitter3": "^5.0.1",
     "react": "^19.0.0",
     "react-dom": "^19.0.0",
     "react-dropzone": "^14.2.3",

frontend/src/services/syncProgress/SyncProgressManager.ts

@@ -1,4 +1,4 @@
-import { EventEmitter } from 'events';
+import { EventEmitter } from 'eventemitter3';
 import { SyncProgressInfo } from '../api';
 
 export type ConnectionStatus = 'disconnected' | 'connecting' | 'connected' | 'reconnecting' | 'error' | 'failed';
@@ -21,7 +21,7 @@ export interface SyncProgressEvents {
  * Provides a clean interface for components to consume sync progress data
  * without being coupled to WebSocket implementation details
  */
-export abstract class SyncProgressManager extends EventEmitter {
+export abstract class SyncProgressManager extends EventEmitter<keyof SyncProgressEvents> {
   protected state: SyncProgressState = {
     progressInfo: null,
     connectionStatus: 'disconnected',
@@ -30,7 +30,7 @@ export abstract class SyncProgressManager extends EventEmitter {
 
   constructor() {
     super();
-    this.setMaxListeners(20); // Prevent memory leak warnings
+    // EventEmitter3 doesn't have setMaxListeners, but it handles listeners efficiently
   }
 
   /**