[levivilet]

Summary

• Update the repository exact Node pin to v26.12.0.
• Include .nvmrc in the existing dependency cache key so entries track the runtime.
• Preserve existing PR, CI, integration, release, e2e, and measurement gates.

Validation

• Node v26.12.0 / npm 11.20.0: npm ci, build, static build, unit tests (107 suites / 323 tests), integration test command, type-check, lint, cache-key generation, and git diff --check passed.
• Local Chromium install stalled during unpacking on the shared filesystem. PR CI retains the existing browser e2e and measurement checks.