Multi-step setup shows progress to the user

Users who don't know how many steps remain in an onboarding flow abandon earlier and report higher frustration scores. WCAG 2.2 SC 2.4.8 (Location) requires that users know where they are within a set of pages — a multi-step onboarding without a step counter violates this directly. Beyond compliance, absence of a progress signal is one of the top controllable causes of onboarding abandonment: users quit because they don't know when it will end, not because the steps are too hard.

Add a step indicator to src/app/(app)/onboarding/layout.tsx that renders on every step transition:

<div className="flex items-center gap-2 mb-6">
  {steps.map((step, i) => (
    <div
      key={step.id}
      className={cn("h-2 flex-1 rounded", i <= currentStep ? "bg-primary" : "bg-muted")}
    />
  ))}
  <span className="text-sm text-muted-foreground ml-2">
    Step {currentStep + 1} of {steps.length}
  </span>
</div>

The indicator must update on every step change. A static label showing the total without the current position does not satisfy the requirement.