Remove unused snapit workflow

[pauloroberto-pozzato]

Removes .github/workflows/snapit.yml, the last workflow in this repo that reads the long-lived secrets.NPM_TOKEN.

Addresses shop/issues#84704.

Why this is safe

• Release publishing remains covered by npm Trusted Publishing/OIDC through .github/workflows/release.yml: it grants id-token: write and sets NPM_TOKEN: "" to force OIDC authentication.
• The unused /snapit snapshot workflow was the only remaining long-lived npm token path in this repo.
• Removing it eliminates the standing NPM_TOKEN exposure from this public repo.

After this change, the only remaining NPM_TOKEN reference is the intentional NPM_TOKEN: "" line in release.yml.

Note: the repository or organization secret should be deleted separately by an admin if it still exists.