fix(release): authenticate cargo with crates.io OIDC

[Iktahana]

Summary

• add the official rust-lang/crates-io-auth-action@v1 OIDC exchange
• pass its short-lived token to cargo publish through CARGO_REGISTRY_TOKEN
• keep the registry existence check introduced in fix(release): publish missing Rust crate version #55

Root cause

id-token: write only allows GitHub to mint an OIDC identity token. Cargo does not exchange it itself, so the previous publish attempt correctly reached cargo publish but failed with no token found.

Verification

• implementation follows the official crates.io Trusted Publishing workflow
• workflow diff passes git diff --check

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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