SDK-613: fix npm ci in the Next.js examples (yalc sig in lockfile)

The `Install` step (`npm run install:all -- ci`) failed on all three CI
legs:

    npm error `npm ci` can only install packages when your package.json
    and package-lock.json ... are in sync.
    npm error Invalid: lock file's @rollbar/react@1.0.0+7da6e313 does
    not satisfy @rollbar/react@1.0.0+d49a5d31

The two lockfiles regenerated for the Next 16 bump recorded
`@rollbar/react` as a *copied* dependency:

    "node_modules/@rollbar/react": {
      "version": "1.0.0+7da6e313",
      "resolved": "file:.yalc/@rollbar/react", ...

That happens under npm 9, whose default for `install-links` is `true`
(npm 10 reverted it to `false`). In copy mode npm pins the version of
the `file:` dependency -- and `install-all.js` publishes the package
with `yalc publish --sig`, so that version carries a build signature
that differs on every machine. Any such lockfile can only ever be
installed on the box that generated it.

Regenerated both with npm 10 / `install-links=false`, which restores
the link form the other examples and `main` already use:

    "node_modules/@rollbar/react": {
      "resolved": ".yalc/@rollbar/react",
      "link": true

The signature now only appears on the `.yalc/@rollbar/react` entry,
which `npm ci` does not verify -- confirmed by rewriting the local
signature to a bogus value and re-running `npm ci`, which succeeds
(main's lockfiles have carried a stale `0.12.0-beta+5817c339` there for
several releases for the same reason).

No dependency versions change. Verified after reinstalling both
examples in link mode: `npm ci`, `eslint .`, `next build` and all six
example tests pass.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: AI Agent