fix(ci): bump TypeScript to 5.x and jest toolchain to 29 to unbreak the build

[mariusz-peplinski]

What

Bump typescript ^4.3.5 → ^5.9.3, and jest/ts-jest/@types/jest 27 → 29.

How it manifested

The Build check fails on every PR and would fail on main too — 50 errors, all inside node_modules:

ERROR in node_modules/@types/node/ffi.d.ts
[tsl] ERROR in node_modules/@types/node/ffi.d.ts(277,28)
      TS1005: ',' expected.
...
webpack 5.109.2 compiled with 50 errors

Not caused by any PR's code. Reproduced on a clean checkout of origin/main (4461bf3) — identical failure.

Why now

package-lock.json is gitignored and CI runs npm install, so every run re-resolves transitive deps from scratch. @types/node has floated to 26.3.0, whose .d.ts files use syntax TypeScript 4.9.5 cannot parse. The last green main build was 2026-04-03, before that bump landed.

Why the jest bump comes along

ts-jest@27.1.4 peer-caps typescript@">=3.8 <5.0", so bumping TypeScript alone makes npm install fail with ERESOLVE. jest 29 + ts-jest 29 lifts the cap.

Also refreshed the stale @ts-jest/dist/types JSDoc type import in jest.config.js (moved to ts-jest in v29).

Verification

On this branch, from a clean node_modules:

• npm install — resolves cleanly, no ERESOLVE
• npm run build — compiles, emits dist/index.js + dist/index.d.ts
• npm test — 53/53 passing, no deprecation warnings

Follow-up worth considering (not in this PR)

The root cause is unpinned CI installs. Committing package-lock.json and switching the workflows to npm ci would make builds reproducible and stop this recurring.