frontend: Refactor namespace playwright for app mode

[vyncent-t]

Description

This PR initiates the refactor of our Playwright test suite by focusing on migrating the namespace tests from the current work on app mode playwright integration to the default Playwright structure. The purpose of this refactor is to ensure compatibility with both web and app modes of the project, laying the groundwork for future improvements and the eventual integration of multi-environment testing (web, app, and in-cluster).

This is the first step in a larger effort to align all Playwright tests with best practices and make them easier to maintain across different environments.

Fixes issue #2332