Cassandra ORM for NestJS

Cassandra ORM wrapper for NestJS (v1.0.5) based on `cassandra-driver`. Provides decorators (`@Entity`, `@Column`), module integration (`forRoot`/`forFeature`), dependency injection (`@InjectMapper`, `@InjectClient`), and a `BaseService` class with CRUD utilities. Differentiator: seamless NestJS module pattern compared to raw driver usage. Stable, low release cadence. Requires peer dependencies: @nestjs/common/core, cassandra-driver 4.x, reflect-metadata, rxjs.