fix(ui): keep enterprise tokens off the Studio Node graph

[kk-agent]

Problem

uvai-enterprise-tokens.ts imported node:fs, pulling Node builtins into the client graph via OneLoopStudio and breaking next build for /studio.

Acceptance

• Token CSS is inlined in uvai-enterprise-tokens.ts with no Node builtins
• src/styles/uvai-enterprise-tokens.css remains the globals.css stylesheet
• Unit test asserts the module stays Node-free and byte-identical to the stylesheet
• npm --workspace=apps/web run build compiles /studio

Context

Canonical closer for PR #2201. Related historical work: #2197 / #2198 (already closed/merged).

[github-actions]

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[linear-code]

GRV-735