Add .prettierrc.json and refactor test files for improved formatting consistency:

- Introduced `.prettierrc.json` to enforce consistent code formatting across the project.
- Updated unit and e2e test files to address formatting issues, improve readability, and ensure alignment with the new Prettier configuration.

.github/workflows/tests.yml

@@ -9,7 +9,26 @@ on:
     - cron: "0 2 * * *"
 
 jobs:
+  format-tests:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: 22
+          cache: npm
+
+      - name: Install dependencies
+        run: npm ci --legacy-peer-deps
+
+      - name: Check frontend test formatting
+        run: npm run format:tests:check
+
   build-and-unit:
+    needs: format-tests
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository