Pin the Fern CLI at 5.168.0 (#183)

## Description

The `nvidia` Fern organization requires Fern CLI 5.168.0 or later from
October 28, 2026. `fern/fern.config.json` still pins 5.95.1, and below
the organization's minimum the CLI quietly re-runs a newer version
through `npx` instead of the pinned one.

Fern 5.168.0 also makes `fern docs md generate` parse library source
locally through Docker. This site declares no `libraries:` and nothing
runs that command, so working on the docs still needs no Docker.

## Release intent

<!-- pair-release-intent:v1 -->
### Changelog title
n/a

### Changelog body
n/a

### Bumps
- services: none
- nvpair-cluster-manager: none
- nvpair-engine-manager: none
- nvpair-errors: none
- nvpair-job-scheduler: none
- nvpair-manual-nodes: none
- nvpair-node-info: none
- nvpair-node-scanner: none
- nvpair-node-settings: none
- nvpair-proxy: none
- nvpair-tui: none
- nvpair-ui-broker: none
- nvpair-workload-manager: none
<!-- /pair-release-intent:v1 -->

## Scope

Only the `version` in `fern/fern.config.json`. No pages, navigation, or
OpenAPI changes.

## Validation

- `npx fern-api@5.168.0 check` from the repository root: 0 errors, 1
warning. The warning is the missing-redirects check, which Fern skips
without a token.
- `npm run typecheck`, `npm run lint`, `npm run dead-code:check`, `npm
run test:unit`, and `npm run service-contracts:check` from `desktop/`.

## Risk

Low. Docs tooling only; no service binary or desktop code changes.

## Checklist

- [x] I have read the [Contributing
Guidelines](https://github.com/NVIDIA/Personal-AI-Router/blob/main/CONTRIBUTING.md).
- [x] Every commit is signed off (`git commit -s`), certifying the
[Developer Certificate of Origin](https://developercertificate.org/).
- [ ] New or existing tests cover the change.
- [x] Relevant documentation is updated.
- [x] I checked the diff, changed filenames, and commit messages for
credentials, private data, internal URLs, internal issue identifiers,
and generated artifacts.
- [x] I recorded the validation commands and results above.
- [x] I declared version bumps in the release-intent block above.
`services/versions.json` is written by automation — do not edit it by
hand.

Signed-off-by: Terve <ntervalon@nvidia.com>

Author: Noah-Tervalon-Nvidia

fern/fern.config.json

@@ -1,4 +1,4 @@
 {
   "organization": "nvidia",
-  "version": "5.95.1"
+  "version": "5.168.0"
 }