DRAFT: EnsembleManager - argument explosion: introduce namespace object

[Polichinel]

DRAFT:

We’re passing way too many loose arguments too deep in the ensemble manager call chain.

We need a namespace object (likely a dataclass) that groups the shared args and gets passed instead of N parameters.

Action:
Dylan + Xiaolong - please define:

1. What the namespace should contain
2. What it should be called
3. Where it should live (ensembles/managers/core?)

Keep it minimal - don’t over-model it - just group the current shared arg clusters.

Goal: replace loose parameter lists in EnsembleManager and sub-calls with a single context/container.