Alert, useToast: Design update

[michaeltaranto]

Alert

Refine the design to use consistent horizontal container inset, aligning content with elements like Card, as well as simplifying the design by removing the sidebar/keyline (consistent with useToast).

useToast

As a means to increase constrast against page content, the design has been updated to be presented on inverted backgrounds based on the color mode.
The design has also be refined to remove the sidebar/keyline (consistent with Alert), while also applying the tone to the provided message.

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🦋 Changeset detected

Latest commit: bbaf97e

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

This PR includes changesets to release 1 package

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braid-design-system	Minor

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[askoufis]

Is the toast action label weight changing to weak intentional? I can't see the change in the code, so I'm not sure how it's happening.

[michaeltaranto]

Yep, it is moving to a weak link as a result inline with the contextual rules built into TextLink — now that it is on surfaceDark it defaults to weak.

We could force regular weight, but the design decision is to run with weak