user-onboarding: tour Next/Previous/custom buttons do nothing on click #87

Describe the bug

In @sourceloop/user-onboarding-client, clicking Next, Previous or a custom button (e.g. Skip) in a tour step does nothing. The tour stays on the current step.

Cause

shepherd.js expects a button's action to be the click handler itself ((this: Tour) => void) and calls it on click. TourButton.action is typed as () => Step.StepOptionsButton['action'], a function that returns a handler.

Under the stricter TypeScript 6 checks that came with the Angular 22 upgrade, the assignments in TourServiceService.actionAssignment were wrapped (b.action = () => handler) to match that type. So on click, shepherd.js gets the handler back but never runs it.

To Reproduce

1. Run a tour with more than one step using the latest library version.
2. Click Next (or Previous / a custom button) on a step.
3. Nothing happens.

Expected behavior

The button runs its handler: it moves to the next or previous step (navigating routes where needed) or runs the custom registered function.

Proposed fix

• Type TourButton.action as Step.StepOptionsButton['action'].
• Assign the handlers directly in actionAssignment again, as before the upgrade.