Add index paramter to toast for proper overlap styling

[cmintey]

Linked Issue

Closes #4264

Description

Toast overlap styling from Zag relies on the use of an --index CSS variable, which is created by Zag when the toast is supplied with an index parameter. This parameter was left out of Skeleton's implementation of the Zag toast.

This PR adds an optional index parameter to a Toast in order to maintain backwards compatibility within the major version. Docs were updated and the Playground was also updated to allow for dynamically changing the toast settings for testing.

While this parameter is optional, I added it to all the docs since it doesn't hurt to be explicit.

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🦋 Changeset detected

Latest commit: 00a4c01

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 5 packages

Name	Type
@skeletonlabs/skeleton-react	Minor
@skeletonlabs/skeleton-svelte	Minor
skeleton	Minor
@skeletonlabs/skeleton-common	Minor
@skeletonlabs/skeleton	Minor

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1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
www.skeleton.dev	Ignored	Preview	Jan 30, 2026 10:08pm

[endigo9740]

@cmintey See my comment below.

And one additional note - I'm going to run this by @Hugos68. As he has a much better handle on the inner workings of Zag. There's two things I'm going to ask of him:

1. Does he agree with my suggested implementation
2. Should we consider sending this upstream in some capacity to Zag; perhaps they can implement a change that makes this even more trivial

In the meantime, let's go ahead and make the changes as I describe below. And as I stated - if it's easier to start with a fresh PR, by all means close this one out. I'd understand given the number of changes.

[endigo9740]

@cmintey again thanks for the quick turn around. Just two super minor things. If need be I can jump in and help with these, just let me know. Thanks again!