Handle duplicate token conflicts gracefully

[JLG-WOCFR-DEV]

Summary

• surface duplicate design token conflicts during normalization instead of overwriting entries and include the conflicting inputs in the response
• ensure the tokens UI blocks duplicate submissions, highlights the offending fields, and announces the error through toast/ARIA messaging
• extend the Playwright tokens spec with duplicate-handling coverage and an API scenario that expects the REST endpoint to report detailed conflicts

Testing

• npx playwright test tests/ui/tokens.spec.js (fails: Docker-based wp-env is unavailable in this environment)

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https://chatgpt.com/codex/tasks/task_e_68dd41f3b84c832ebabf3cb50d349af9

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Preserve last CSS definition when importing duplicate tokens

convertCssToRegistry used to index declarations by name so the last occurrence replaced earlier ones, mirroring CSS’s cascade. After the change the code simply appends tokens and relies on normalizeRegistry() to deduplicate, which keeps the first encountered value. If the CSS source contains duplicate custom properties, importing the registry now yields the stale initial value, so a round‑trip through the admin UI will overwrite the effective CSS value with an older one and duplicates still aren’t surfaced. The import needs to retain last‑wins behaviour or explicitly pick the final conflicting token as canonical.

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