Update v21 to the supported Jasmine 6 toolchain - #331

Summary

• upgrade jasmine-core to 6.3.0 and @types/jasmine to 6.0.0 together
• align packageManager with npm 11.12.1 used by CI
• regenerate the lockfile with npm 11.12.1 while retaining the required @emnapi packages

Validation

• clean npm ci with Node 24.15.0 and npm 11.12.1
• npm run lint
• npm test
• npm run build:demo
• npm audit --omit=dev --audit-level=high
• npm run verify:package
• npm run verify:consumer