Fix npm verification for Vitest consumers

[RolandSall]

Summary

• pin npm 11.19.1 in the release workflow
• run published-consumer installs through the same pinned npm version
• document the updated trusted-publishing toolchain

Verification

• reproduced the npm resolver crash with Vitest 4.1.11 alone on npm 10.9.4 and 11.5.1 using a clean cache
• verified Vitest 4.1.11 installs with npm 11.19.1
• verified build, generated clients, typecheck, lint, and diff checks
• previously verified the full published 0.1.0 consumer matrix after successful installation