fix(app): prevent race conditions in UI initialization and upload modal

- Move `initializeUserInterface()` earlier in `app.init()` to ensure button listeners (like Upload) are bound before potentially slow network operations (Access Control, Relay connection) block or delay responsiveness.
- Make `UploadModal.open()` async and await `load()` to ensure the DOM is ready before removing the `hidden` class.
- Stabilize `notification-system.spec.ts` by adding a wait for app settlement.
- Update visual test baselines.

Co-authored-by: PR0M3TH3AN <[email protected]>

js/app.js

@@ -1212,12 +1212,14 @@ class Application {
       await this.initializeServices();
 
       const modalPromise = this.initializeUIResources();
+
+      // Initialize UI listeners early so buttons are responsive while network connects
+      this.initializeUserInterface();
+
       await this.initializeNetwork();
       await modalPromise;
 
       await this.initializeDataAndSession();
-
-      this.initializeUserInterface();
       await this.performAutoLogin();
 
       await this.finalizeInitialization();