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.

tests/e2e/pos-customer-rules.spec.js

@@ -56,8 +56,10 @@ test("rules tab reloads customer attributes when the panel becomes visible", asy
   await expect(rulesTab).toBeVisible();
 
   const customerAttributesResponse = page.waitForResponse((response) => {
-    return response.request().method() === "GET"
-      && response.url().includes(`/customer/attributes?customer_number=${customer.customerNumber}`);
+    return (
+      response.request().method() === "GET" &&
+      response.url().includes(`/customer/attributes?customer_number=${customer.customerNumber}`)
+    );
   });
 
   await rulesTab.click();