`extract` reports extraction errors / exits with code 1 for APIs using `set-body template="liquid"` with `{{ }}` expressions

### Command that triggered the bug

apiops extract --log-level debug --resource-group --service-name --output ./artifacts --filter ./configuration.extractor.yaml --subscription-id --remove-stale

### Expected behavior

Extraction completes with exit code 0 for an API whose policy uses `set-body template="liquid"` to build or transform a request/response body, as long as the API and its real named values/backends actually exist and are reachable.

### Actual behavior

The extraction otherwise finishes fine. All APIs, operations, and real named values get written to the output directory. But the run still reports errors and exits with code 1:

```
[INFO] Extraction complete: 19 resources extracted, 4 errors
```

With `--log-level debug` on, I can see the CLI issuing `GET .../namedValues/` requests where `` isn't a named value at all. It looks like it was pulled straight out of a `{{ ... }}` expression inside one of our `set-body template="liquid">` blocks:

```
[DEBUG] HTTP GET https://management.azure.com/.../namedValues/context.Request.MatchedParameters%5B%22id%22%5D?api-version=2025-09-01-preview
[DEBUG] HTTP GET https://management.azure.com/.../namedValues/body.envelope.body.Test_Result.test?api-version=2025-09-01-preview
[DEBUG] HTTP GET https://management.azure.com/.../namedValues/body.envelope.body.fault.faultcode?api-version=2025-09-01-preview
[DEBUG] HTTP GET https://management.azure.com/.../namedValues/body.envelope.body.fault.faultstring?api-version=2025-09-01-preview
```

None of those are named values in our APIM instance. They're Liquid interpolation expressions from a `set-body template="liquid"` policy we use to build a SOAP request and reshape the SOAP response into JSON. Each lookup 404s, and each 404 seems to get counted toward the "errors" total. That matches up exactly: 4 Liquid expressions, 4 reported errors. The nonzero exit code then fails our CI pipeline step even though nothing is actually broken or missing.

To work around this we rewrote the affected `set-body template="liquid">` blocks as plain C# expressions (`@{ ... return ...; }`) instead of Liquid templates. That removed the `{{ }}` syntax from the policy entirely, and the same extraction now completes with 0 errors and exit code 0. But with the Liquid template the policy would be easier to read and understand.

### apiops CLI version

1.0.1

### Environment details

- Azure DevOps pipeline, Ubuntu 24.04 hosted agent
- Node.js 24.x
- `apiops extract` invoked via `npx`, with `--filter` pointing at a YAML filter config
- The affected API's policy has three `` blocks: one building a SOAP request body (interpolating a template parameter), and two transforming the SOAP response into JSON (interpolating values pulled out of the parsed SOAP envelope)

### CI/CD environment

Azure DevOps

### Is this bug blocking you?

No

まず、`{{ }}` 式を含む `set-body template="liquid"` を設定した API ポリシーに対して、報告された `apiops extract` コマンドを実行し、デバッグログを使用して named value の検索を追跡します。ポリシー式を解析する抽出パスをたどり、Liquid 式が named values として扱われていないことを確認します。参照された API リソースが有効な場合に、抽出でエラーが 0 件と報告され、コード 0 で終了すれば完了です。

索引モデルが issue の本文から書いたものです。