Hardens the release workflow against command/string injection from the workflow_dispatch version input (GHSA-749g-253p-pqxv). We assessed that advisory as not a security vulnerability because triggering the workflow already requires write access and the main environment enforces required reviewers, but the underlying interpolations are worth fixing as defense in depth.

• Validate the version input against a semver pattern before any step runs.
• Pass version, github.ref, and GITHUB_TOKEN to run steps via env with quoted expansion instead of unquoted inline interpolation.
• In build/sync-version.js, serialize the version into lib/meta.js with JSON.stringify so a crafted value cannot break out of the generated string literal.

Verified the semver check accepts valid versions (including v-prefixed and prerelease) and rejects injection payloads, the meta.js generator safely quotes a malicious payload instead of executing it, and node test/internals/version.test.js still passes.