- Replaced all mentions of "DTOs" with "entities" across CLAUDE, README, and workflow files to align terminology consistently.
- Updated examples, code snippets, and directory references to reflect the new structure (e.g., `dtos` to `entities`).
- Simplified explanation of entity usage in nested objects and arrays within documentation.

…ure/SRV-359/entity_2

…ties

- Remove nested Gate::API namespace structure from controllers, entities, and treaties
- Reorganize treaty files from gate/api/* to top-level directories (languages, movies, posts, users)
- Simplify entity structure by removing intermediate request/response directories
- Update routes configuration to reflect new non-namespaced structure
- Update all related specs to work with new directory organization

This change flattens the API structure, making it easier to navigate and maintain
while reducing unnecessary nesting layers.

- Introduced domain-based directory structure under `app/entities/`.
- Split entities into `requests`, `responses`, and `shared` modules for clarity.
- Refactored entity names to follow a consistent naming convention (e.g., `Posts::Create::RequestEntity`).
- Updated all documentation and examples to reflect the new entity structure.
- Replaced inline nested entity definitions with reusable shared entities wherever applicable.

- Introduced `Posts::CreateTreaty` as the base class for treaty definitions.
- Updated all documentation and examples to replace inline entities with structured references (e.g., `Create::RequestEntity` -> `Posts::Create::RequestEntity`).
- Updated request and response definitions in treaty-related files to align with the standardized class structure.
- Improved consistency across examples in API reference, cheatsheet, and core concepts documentation.

- Updated all treaty definitions to use fully qualified entity class names (e.g., `Create::RequestEntity` -> `Posts::Create::RequestEntity`).
- Adjusted documentation, examples, and specs to reflect the changes.
- Ensured consistent reference updates across CLAUDE, API reference, cheatsheet, core concepts, examples, and sandbox files.