/**
 * Denotes that a bean should be created as a singleton instance.
 * <p>
 * Singleton-scoped beans are instantiated once and reused throughout the entire
 * Maven execution. This scope should be used for stateless services or components
 * that can be safely shared across the entire build process.
 * <p>
 * Example usage:
 * <pre>
 * {@literal @}Singleton
 * public class GlobalConfiguration {
 *     // Implementation
 * }

 * resulting XML document is parsed, the parser API will return this text as the original literal
 * string {@code "Foo<Bar>"}.
 *
 * <p>An {@code Escaper} instance is required to be stateless, and safe when used concurrently by
 * multiple threads.
 *
 * <p>Because, in general, escaping operates on the code points of a string and not on its

### Service
- Inject behaviors (Bhv) for data access
- Use `OptionalEntity<T>` for nullable returns
- Plain classes (no extends/implements)

### Helper
- Stateless utility classes
- Access via `ComponentUtil.getXyzHelper()`
- Named with "Helper" suffix

### DBFlute Generated Code
```
opensearch/{index}/
├── bsentity/, bsbhv/    # Base classes (DO NOT EDIT)

	// message will be sent after the serialized message as little endian.
	FlagCRCxxh3 Flags = 1 << iota

	// FlagEOF the stream (either direction) is at EOF.
	FlagEOF

	// FlagStateless indicates the message is stateless.
	// This will retain clients across reconnections or
	// if sequence numbers are unexpected.
	FlagStateless

	// FlagPayloadIsErr can be used by individual ops to signify that

 * resulting XML document is parsed, the parser API will return this text as the original literal
 * string {@code "Foo<Bar>"}.
 *
 * <p>A {@code CharEscaper} instance is required to be stateless, and safe when used concurrently by
 * multiple threads.
 *
 * <p>Popular escapers are defined as constants in classes like {@link
 * com.google.common.html.HtmlEscapers} and {@link com.google.common.xml.XmlEscapers}. To create