Scope potential workflow interface between CMEW and REF

Depends on #296, #333, #320 (sub-issues of #280)

As noted in https://github.com/MetOffice/CMEW/issues/295#issuecomment-3743818366:

> If we are looking a compatibility with CMEW, I think we can replace esmvaltool block with REF, CDDS will still be needed.
>
> But there are some limitations which needs to address. CMEW model id and suite id which might not be possible in REF. Differentiating different model run might be problematic and might need to re-design the workflow.

There are likely options for how to use or align with the REF and include standardisation of model development data. This investigation will scope design options, summarise high-level pros and cons of these options, and make recommendations for either investigation or implementation.

Plan for design - meeting next week. All to bring ideas, constraints. Aim for meeting is to agree design for interface(s).
Potentially separate interfaces (CMEW tasks) for each of ingest, solve, display

Start by reviewing dependencies #296, #333, and #320, along with the discussion in #295. Use the planned meeting context to compare interface options for ingest, solve, and display, including model and suite identification constraints. Done means documenting high-level pros and cons and recommending follow-up investigation or implementation.

Written by the indexing model from the issue text.