feat: programmatic rooms.Room API for embedding

[rosspeili]

Problem Statement

Currently, the only way to interact with the Rooms framework is via the interactive cli.py wizard. This makes it impossible for developers to import Rooms as a library into their own Python applications, web backends, or automated pipelines.

Proposed Solution

1. Refactor the core logic in session.py to be fully stand-alone and decoupled from the CLI.
2. Expose a clean, high-level Room class (or similar) in the rooms package.
3. The API should look something like:

   from rooms import Room, SessionConfig, AgentConfig
   
   config = SessionConfig(topic="...", agents=[...])
   room = Room(config)
   for turn in room.stream():
       print(turn.content)

Alternatives Considered

None. A programmatic entry point is essential for the framework's growth and adoption by the developer community.

Priority

Medium 🟡

Additional Context

This will serve as the foundation for the upcoming --config headless execution mode.