Fix EditorConfig lint errors

## EditorConfig Linting Failures

Linting failures were detected in the automated EditorConfig lint workflow run.

### Workflow Details

- Run: https://github.com/stdlib-js/stdlib/actions/runs/26006953643
- Type: EditorConfig Linting
- Date: 2026-05-18 00:21:37 UTC

### Error Details

```
Linting files for basic formatting errors...
Downloading v3.6.1
lib/node_modules/@stdlib/ndarray/base/slice-assign/examples/index.js:
78-94: Wrong indentation type(spaces instead of tabs)

1 errors found
make: *** [/home/runner/work/stdlib/stdlib/tools/make/lib/lint/editorconfig.mk:90: lint-editorconfig-files] Error 1
```

### Pull Request Instructions

- Please use the following PR title format:
"chore: fix EditorConfig lint errors (issue #)".
- Reference this issue in the "Related Issues" section of the PR body as "resolves #".

从 lib/node_modules/@stdlib/ndarray/base/slice-assign/examples/index.js 开始，检查第 78-94 行，其中 EditorConfig workflow 报告使用了空格而不是制表符。运行 EditorConfig lint workflow 或 tools/make/lib/lint/editorconfig.mk 中的 lint-editorconfig-files target。lint 不报告格式错误即表示完成。

由索引模型根据 Issue 内容生成。