Add shouldStopAtNode callback to closestDataStack

[joshhanley]

The Scenario

When Livewire contextualises wire:click expressions, it prefixes bare identifiers with $wire. so they resolve against the component. For example, wire:click="$js.select(user)" becomes $wire.$js.select($wire.user).

To support Alpine-scoped variables (like x-for iteration items), Livewire needs to check Alpine's scope chain before prefixing. However, closestDataStack traverses all the way up the DOM tree, which means Alpine scope from outside the Livewire component can incorrectly override $wire properties.

The Problem

There's currently no way to tell closestDataStack where to stop collecting scope. It always traverses to the root of the document.

The Solution

Add an optional shouldStopAtNode callback parameter to closestDataStack. When provided, the function stops traversing and returns an empty array if shouldStopAtNode(node) returns true.

// Default behaviour (unchanged)
Alpine.closestDataStack(el)

// Stop at a specific boundary
Alpine.closestDataStack(el, node => {
    return node.hasAttribute && node.hasAttribute('wire:id')
})

This allows Livewire to collect Alpine scope only within the component boundary.

[calebporzio]

change this to undefined callback plus conditional

[joshhanley]

Closed as we decided not to add the change to Livewire for now, that required this PR.