Update @cortex-js/compute-engine to 0.126.1

[Copilot]

@cortex-js/compute-engine was pinned to a stale version (0.100.0 in npm deps, 0.55.6 in the CDN imports used at runtime). This bumps everything to the latest release, 0.126.1.

Dependency manifests

• Added package.json declaring @cortex-js/compute-engine@^0.126.1 (these files did not yet exist on this branch)
• Generated package-lock.json against the npm registry, locking 0.126.1 and its updated transitive deps (@arnog/colors@0.7.0, complex-esm@2.1.1-esm1)

Runtime CDN imports

• src/teachbooks_questions/_static/teachbooks_sab.js and teachbooks_sag.js: bumped the esm.run import from @0.55.6 to @0.126.1

- import { ComputeEngine } from "https://esm.run/@cortex-js/compute-engine@0.55.6";
+ import { ComputeEngine } from "https://esm.run/@cortex-js/compute-engine@0.126.1";

No logic changes — this is purely a version alignment across the dependency manifest and both CDN import sites.

[Tom-van-Woudenberg]

Included manually in #27