fix(ci): install firefox for e2e-headless job and harden ui tests\n\n- Updated .github/workflows/ci.yml to install firefox in the e2e-headless job, resolving \"Executable doesn't exist\" errors.\n- Added defensive null checks in UploadModal.js to prevent runtime crashes during reset.\n- Hardened login-flows.spec.ts to prevent flaky logout assertions.

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

.github/workflows/ci.yml

@@ -478,7 +478,7 @@ jobs:
         run: npm ci
 
       - name: Install Playwright browsers
-        run: npx playwright install --with-deps chromium
+        run: npx playwright install --with-deps chromium firefox
 
       - name: Run headless E2E tests
         run: npm run test:e2e