Validate the bundled CSS entry in beta and accept ADR-0010 before the flip

[pomfrida]

Part of #4740 (feeds the flip described in ADR-0009 and the beta verification in #5120).

ADR-0010 (#5199) is deliberately Proposed: it must be validated on the beta line before it is accepted and the flip maps ./css/variables to the bundle.

Validation steps (from the ADR)

• Use next/css/variables.css (from Add a bundled variables.css to the Tokens Studio release workflow #5201) in the /next component migration and let beta testers exercise it
• Settle the remaining open question: whether anything beyond colour needs mode files bundled as the token architecture rework lands (density set may change shape)
• At the flip, map ./css/variables to the bundle per ADR-0009's exit plan — at least one beta must expose the exact 3.0.0 export surface

Done when ADR-0010 is marked Accepted and the flip release ships the bundle on the final specifier.

[claude]

These issues look closely related, part of the same eds-tokens 3.0.0 CSS/colour-scheme flip (beyond the ones already linked in the description):

• Document the CSS import and colour-scheme changes in the 3.0 migration guide #5203 — Document the CSS import and colour-scheme changes in the 3.0 migration guide (open): the migration-guide counterpart to this flip, documenting the exact CSS import change this issue validates.
• docs: add ADR for attribute-scoped colour-scheme switching over light-dark() #5200 — docs: add ADR for attribute-scoped colour-scheme switching over light-dark() (open): the sibling ADR for the colour-scheme half of the same 3.0 change surface being flipped and documented.

This comment was generated by an LLM and may be inaccurate. Please verify that the linked issues are actually relevant.