chore: shorten tokenlist CDN cache and invalidate it after upload

[hurricanenara]

Note

Low Risk
CI-only change to cache headers and an optional CloudFront invalidation; no application auth or data-path changes, though enabling the step requires correct IAM and repo vars to avoid failed runs.

Overview
Updates the Generate Uniswap Token List workflow so fresh token merges reach downstream consumers (e.g. tokens API polling every ~20 minutes) sooner.

The S3 upload now sets Cache-Control: max-age=300 (was 3600), shortening how long the CDN may serve a stale copy without an explicit purge.

A new Invalidate CDN cache step runs aws cloudfront create-invalidation for /${{ env.S3_PATH }} when the repo variable STATIC_CF_DISTRIBUTION_ID is set; otherwise it is skipped until that variable and cloudfront:CreateInvalidation on the S3 role are configured.

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