Kolibri-Onboarding: Tour persists over slow network — should wait for step elements before starting on reload

[shruti862]

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Desired behavior

The onboarding tour should only start once all step elements for the current page are present in the DOM. This ensures that each target element defined in onboardingSteps is available when the tour begins, regardless of network speed or page reload conditions.

Current behavior

On slower networks and when reloading a page, the tour sometimes starts before all DOM elements have rendered. As a result, some steps cannot find their target elements, which leads to the dimmed overlay background appearing without the onboarding modal being displayed. This results in a broken tour experience.

https://github.com/user-attachments/assets/863e4e85-7e43-4a3e-99ed-109177f1ce26