The `runner.environment` context is shown as invalid in this extension.

**Describe the bug**
When we use the `runner.environment` context listed in [official document](https://docs.github.com/en/actions/writing-workflows/choosing-what-your-workflow-does/accessing-contextual-information-about-workflow-runs#runner-context), this extension reports "Context access might be invalid".

**To Reproduce**
Steps to reproduce the behavior:
1. With this workflow '...'

```yaml
steps:
- if: ${{ runner.environment == 'github-hosted' }}
run: echo "This is a ${{ runner.environment }} runner"
```

2. Do this '...'

Open the "Problems" Panel.

3. See error\

```plain
Context access might be invalid: environment
```

**Expected behavior**
The `runner.environment` context listed in [official document](https://docs.github.com/en/actions/writing-workflows/choosing-what-your-workflow-does/accessing-contextual-information-about-workflow-runs#runner-context) can be recognized well by this extension.

**Screenshots**

**Extension Version**
`v0.27.0`

**Additional context**
Add any other context about the problem here.

Start by reproducing the supplied workflow snippet in the extension and inspect the context-validation path that produces the Problems-panel warning. The work is done when runner.environment is recognized according to the linked GitHub Actions runner-context documentation and the warning no longer appears for this expression.

由索引模型根据 Issue 内容生成。