Class ServiceWriter

Generates NestJS service classes with dual HTTP transport methods.

Dual Method Strategy:

• Observable Method (suffix $): Issues raw HTTP calls via HttpService, returns Observable<T>.
• Promise Method: Wraps the Observable sibling using firstValueFrom(), returns Promise<T> for convenience.

Both methods share the same URL construction, parameter binding, and error handling logic; the Promise variant simply adapts the Observable for async/await patterns.

Each service includes:

• Dependency injection of HttpService via constructor.
• Type-safe operation methods derived from OpenAPI operationIds.
• JSDoc descriptions from OpenAPI operation summaries.
• Standard file header with generation metadata.