Register External Component page links to a non-existent flat inference/switch-providers path

## Description

The published "Register an External Component During Onboarding" page contains a relative link whose target path does not exist. Following the "Switch Inference Providers" link returns HTTP 404.

**Platform scope:** Published documentation content issue, independent of client platform; reproduced by direct URL fetch.
**Regression:** Unknown — earlier documentation versions not tested.
**OpenShell issue:** No.

## Environment

```text
Device: Documentation validation workstation
OS: macOS
Architecture: arm64
Node.js: N/A - static published-document validation only
npm: N/A - static published-document validation only
Docker: N/A - static published-document validation only
OpenShell CLI: N/A - static published-document validation only
NemoClaw: N/A - static published-document validation only
OpenClaw: N/A - static published-document validation only
```

## Steps to Reproduce

1. Open https://docs.nvidia.com/nemoclaw/deployment/register-external-component
2. In the "Select Interceptor-Supplied Policy" section, find the "Switch Inference Providers" link.
3. Follow the link. Its target resolves to `https://docs.nvidia.com/nemoclaw/inference/switch-providers`
4. Observe that this target returns HTTP 404.

## Expected Result

The link resolves to a real, existing documentation page describing how to switch inference providers/models for a sandbox.

## Actual Result

The target `https://docs.nvidia.com/nemoclaw/inference/switch-providers` returns "This page does not exist" (HTTP 404). The `.md` variant of the same path also 404s.

The site's actual content for this topic is published under per-agent-runtime nested paths instead of the flat path this link assumes:

- `/nemoclaw/user-guide/openclaw/inference/manage-inference/switch-providers`
- `/nemoclaw/user-guide/deepagents/inference/manage-inference/switch-providers`
- `/nemoclaw/user-guide/hermes/inference/manage-inference/switch-providers`

The Register External Component page's own content is agent-runtime-agnostic, so it is unclear which of the three (if any single one) the link is meant to target.

Every other link on the page (CLI commands reference, its `--apf-interceptor` anchor, gateway lifecycle authority, host files and state) was individually verified reachable with content consistent with the page's references.

## Logs

```text
Not captured - static published-document validation only, no terminal/application log applies.
```

Start at the published Register External Component During Onboarding page and inspect the broken relative link in the Select Interceptor-Supplied Policy section. Compare the three listed per-agent-runtime switch-providers paths, determine the intended destination for this agent-runtime-agnostic page, update the link, and verify the published target no longer returns HTTP 404.

Written by the indexing model from the issue text.