CI test runs share one Mongo test DB — two overlapping builds fail each other at random

[JoshuaVSherman]

Summary

• Update Node.js engine requirement to 24.18.1 in package.json and .nvmrc.
• Update CircleCI executor image tag to cimg/node:24.18.1-browsers in .circleci/config.yml.
• Bump package.json version to 2.11.3.

Part of #1017

How to test locally

1. Run full test suite and quality checks:

npm test

2. Verify all ESLint, jscpd, typecheck, and vitest unit tests pass 100% green.
3. Verify .circleci/config.yml docker image tag points to cimg/node:24.18.1-browsers.

Test evidence

Test Files  68 passed (68)
     Tests  635 passed (635)

🤖 Work by agy — Gemini 3.6 Flash (High)