Add a declarative config abstraction for data-import sources

Add a declarative config abstraction for data-import sources: a task in MiMo-V2.6-RL-oss: Agentic RL Environments (MiMo RL release). Our data-import sources hand-roll a lot of boilerplate to turn loosely-typed dictionaries (coming from API requests and from rows stored in our database) into typed…

The task

Our data-import sources hand-roll a lot of boilerplate to turn loosely-typed dictionaries (coming from API requests and from rows stored in our database) into typed configuration objects. We want a small, reusable abstraction built on top of the standard library's dataclasses…

Part of XiaomiMiMo/MiMo-V2.6-RL-oss.