Fix: use Node's built-in fetch to avoid Electron/Node 24.17.0 'Premature close' (#99)

[randomBrainstormer]

Summary

Fixes the Premature close failure reported in #99, which breaks OAuth token refresh and calendar fetches on current Electron builds.

The root cause (thoroughly diagnosed by @daotsc in #99) is an upstream Node.js 24.17.0 regression (nodejs/node#63989), already fixed in a later 24.x. gaxios (google-auth-library's HTTP transport) falls back to the node-fetch@2 package when there's no browser window global — i.e. node_helper.js running inside MagicMirror's Electron main process — and that combination trips a false-positive ERR_STREAM_PREMATURE_CLOSE on Node 24.17.0's keep-alive path.

Fix

Point gaxios at Node's built-in fetch (undici) via its documented fetchImplementation option. undici has its own connection pool and never touches http.Agent, so it sidesteps the regression. Both the token refresh and the events.list call go through the OAuth2 client's transporter, so a single injection point covers both.

Why this approach (vs #100)

#100 fixes the same issue by replacing googleapis with hand-rolled https calls. This PR is a smaller alternative that:

• keeps the entire googleapis stack (auto token-refresh persistence, error typing, future API compatibility) instead of reimplementing it;
• requires no re-authentication — it doesn't change the token.json format, so existing users keep working after updating;
• is ~28 lines and adds no dependencies.

Testing

• npm test — 30/30 passing
• npx eslint node_helper.js — clean
• Verified at runtime that the native fetch is attached to the transporter used for both the token refresh and the events.list dispatch.

⚠️ Needs confirmation on a machine that reproduces the bug (Electron 42.5.2 / Node 24.17.0). Asked the original reporter to verify.

[jhaywood-sys-pi]

Updating my GoogleCalendar module to this branch has resolved the Premature Close error for me and allowed the calendar to be displayed again.

[irsx02]

@randomBrainstormer - can you merge your new changes to the main branch?