feat: add npm template support

Add support for using npm packages as templates when creating new
projects. This feature allows users to specify custom templates
from npm registry with optional version control.

Key features:
- Support multiple npm template formats (npm:, @scope/package, package-name)
- Add --template-version flag for version specification
- Implement smart caching mechanism (.temp-templates/)
- Support flexible template structures (template/, templates/app/, root)
- Isolated installation to prevent workspace conflicts
- Export utility functions for downstream projects

Example usage:
  npm create rsbuild@latest my-project -- --template my-template
  npm create rsbuild@latest my-project -- --template @scope/template
  npm create rsbuild@latest my-project -- --template my-template --template-version 1.2.3

API exports:
  - isNpmTemplate()
  - resolveCustomTemplate()
  - resolveNpmTemplate()
  - sanitizeCacheKey()

Inspired by sparkling's npm template implementation.

Author: Huxpro

README.md

@@ -17,6 +17,65 @@ A shared package for create-rspack, create-rsbuild, create-rspress and create-rs
 npm add create-rstack -D
 ```
 
+## Features
+
+### NPM Template Support
+
+`create-rstack` supports using npm packages as templates, allowing users to create projects from custom templates published to npm.
+
+#### Usage
+
+```bash
+# Using npm package name
+npm create rsbuild@latest my-project -- --template my-template-package
+
+# Using scoped package
+npm create rsbuild@latest my-project -- --template @scope/template-package
+
+# Using explicit npm: prefix
+npm create rsbuild@latest my-project -- --template npm:my-template-package
+
+# With specific version
+npm create rsbuild@latest my-project -- --template my-template-package --template-version 1.2.3
+```
+
+#### Template Package Structure
+
+Your npm template package should have one of the following structures:
+
+```
+my-template-package/
+├── template/              # Preferred
+│   ├── package.json
+│   └── src/
+├── templates/
+│   └── app/              # Alternative
+└── (root)                # Fallback
+    ├── package.json
+    └── src/
+```
+
+#### Caching Strategy
+
+- Templates with `latest` version are always re-installed to ensure the latest version
+- Specific versions are cached in `.temp-templates/` for faster reuse
+
+#### API
+
+```typescript
+import {
+  isNpmTemplate,
+  resolveCustomTemplate,
+  resolveNpmTemplate,
+} from 'create-rstack';
+
+// Check if template input is an npm package
+if (isNpmTemplate(templateInput)) {
+  // Resolve npm template to local path
+  const templatePath = resolveCustomTemplate(templateInput, version);
+}
+```
+
 ## Examples
 
 | Project | Link                                                                                         |