chore(deps): update Node.js to 24.20.0

[lopopolo]

Summary

• update the Node.js LTS pin from 24.19.0 to 24.20.0

Upstream review

• exact comparison reviewed: nodejs/node@v24.19.0...v24.20.0
• release metadata: https://github.com/nodejs/node/releases/tag/v24.20.0
• released 2026-08-26, so the full seven-day cooldown has elapsed
• the Node module ABI and V8 version are unchanged; the release updates npm from 11.17.0 to 11.19.0, refreshes CA roots, and contains additive features and fixes
• risk: low; this repository uses Node only for its pinned pnpm/Prettier formatting toolchain

Other sweep decisions

• pnpm 12.1.0 is cooldown-eligible but changes runtime downloads, global shims/PATH behavior, git transport, and store/cache placement; it requires human review under the dependency runbook
• pnpm 11.26.0 and pnpm 12.2.0 through 12.3.4 remain inside the cooldown
• Zizmor 1.30.0 is being handled as a separate logical dependency domain
• Ruby 3.4.10, cargo-deny 0.20.2, cargo-mutants 27.1.0, and cargo-outdated 0.19.0 are current
• ucd-generate remains with the Unicode automation because updating it changes generated Unicode tables
• no open Dependabot pull requests were present

Validation

• mise run fmt
• mise run lint
• mise run test (104 unit tests and 33 doc tests)
• cargo package --allow-dirty