✅(e2e) remove some flakiness

Service worker added some flakiness, we
activate the sw only if not from the CI.
We add as well the email of the user added in a
doc to the toast message. This way we can check
if the user was added correctly, this will remove
some flakiness in some tests.

src/frontend/apps/impress/package.json

@@ -5,7 +5,7 @@
   "scripts": {
     "dev": "next dev",
     "build": "prettier --check . && yarn stylelint && next build",
-    "build:ci": "cp .env.development .env.local && yarn build",
+    "build:ci": "cp .env.development .env.local && cross-env NEXT_PUBLIC_CI=true yarn build",
     "build-theme": "cunningham -g css,ts -o src/cunningham --utility-classes",
     "start": "npx -y serve@latest out",
     "lint": "tsc --noEmit && next lint",
@@ -22,6 +22,7 @@
     "@openfun/cunningham-react": "2.9.3",
     "@tanstack/react-query": "5.40.1",
     "grapesjs-blocks-basic": "1.0.2",
+    "cross-env": "*",
     "i18next": "23.11.5",
     "lodash": "4.17.21",
     "luxon": "3.4.4",