Fix BLAKE3 size validation

[marko1olo]

Fixes #2512.

Summary

• validate the BLAKE3 output size before passing it to @noble/hashes
• convert negative and fractional size values into a controlled OperationError
• add regression coverage for -6 and 1.2 size values

Checks

• node --no-warnings --no-deprecation --openssl-legacy-provider tests/operations/index.mjs -> 1962 passing
• npx eslint src/core/operations/BLAKE3.mjs tests/operations/tests/BLAKE3.mjs
• npx grunt configTests
• git diff --check

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}