test: add Cypress E2E test for Audit Trails CSV download

- Added comprehensive E2E test to prevent CSV download regression
- Implemented stable error toast verification to avoid false positives
- Updated .browserslistrc to remove outdated browser versions
- Refined .gitignore to exclude only Cypress-generated artifacts
- Configured proper test selectors and wait strategies

Addresses: WEB-493

cypress.config.ts

@@ -11,7 +11,8 @@ export default defineConfig({
     setupNodeEvents(on, config) {
       return require('./cypress/plugins/index.ts')(on, config);
     },
-    baseUrl: 'http://localhost:4200'
+    baseUrl: 'http://localhost:4200',
+    experimentalStudio: true // enable Cypress Studio
   },
 
   component: {