Provide Spring Boot Starter for Atto Commons

[rotilho]

All Atto backend applications (including the Node) are built on Spring, which makes a Spring Boot Starter a natural addition to the ecosystem. A dedicated starter would simplify integration by centralizing configuration and conventions.

Potential features include:

• Type Converters: Auto-register converters for core Atto types (e.g., AttoAmount, AttoAddress) so they can be seamlessly used in controllers and request parameters.
• OpenAPI/Swagger Support: Provide out-of-the-box schema definitions and annotations for Atto types, ensuring consistent and accurate OpenAPI documentation across services.
• Default Configurations: Common beans, serializers/deserializers, and validation setup pre-configured to reduce boilerplate.

This starter would improve developer experience, reduce duplicated configuration, and ensure consistency across Atto-based Spring Boot projects.