Scripts in .ci/scripts/ are never linted and report 'process is not defined'

## Summary

JavaScript under `.ci/scripts/` is not covered by the ESLint hook or by ESLint's
Node globals configuration. Running ESLint against those files by hand reports
`'process' is not defined` for every use, because they fall through to the
browser-globals config.

## Evidence

```
$ npx eslint .ci/scripts/check-release-notes-version.js
344:5 error 'process' is not defined no-undef
344:59 error 'process' is not defined no-undef
...
✖ 13 problems (7 errors, 6 warnings)
```

Two gaps combine:

- `lefthook.yml` -- the `lint-js` hook globs only `assets/js/*.{js,ts}`, so
`.ci/scripts/**` is never linted on commit.
- `eslint.config.js` -- the Node-globals block covers `helper-scripts/**/*.js`
and `scripts/**/*.js`, but not `.ci/scripts/**/*.js`.

Prettier is unaffected: its hook globs `*.{css,js,ts,jsx,tsx}`, so staged
`.ci/scripts` files are formatted, and existing files there are Prettier-clean.

## Impact

CI scripts are the code most likely to fail silently in a way nobody notices, and
they get the least static checking of any JavaScript in the repo. Anyone who does
run ESLint on them sees a wall of false `no-undef` errors, which trains people to
ignore the output.

## Suggested fix

Add `.ci/scripts/**/*.js` to the Node-globals block in `eslint.config.js`, then
extend the `lint-js` glob to cover it. Expect to fix real findings in the
existing scripts once the false `no-undef` noise is gone.

## Notes

Found while adding `.ci/scripts/check-v1-shared-drift.js` during the InfluxDB v1
shared-content migration. That script has unit tests
(`check-v1-shared-drift.test.js`, run via `node --test`), but no lint coverage --
same as its neighbors.

Start with lefthook.yml and eslint.config.js, then run npx eslint .ci/scripts/check-release-notes-version.js to separate false globals errors from real findings. Check the existing .ci/scripts files, including check-v1-shared-drift.js and its check-v1-shared-drift.test.js test run via node --test. Done means the scripts are covered by the hook and Node globals configuration, with remaining lint findings addressed.

Written by the indexing model from the issue text.