[Feature]: Guidance on how we use AI within the DfE

### Description

Suggested at the DISD away day, we could do with a framework around how we expect AI to be used by analysts within the DfE.

I guess sections along the lines of:
- Using AI prompting to generate draft FOI / PQ responses
- How AI is used in EES
- How AI can be used to optimise code
- vectorisation
- code consolidation (converting to functions)
- AI in QA

### Use case

As an analyst I want to know how I can / should use AI in my day to day work

### Why this is important

Help give analysts confidence / security on how they can use AI

### Additional Context

Would be good to break this up and get input / case studies from teams on how they do some of this.

Start by turning the listed use cases into a proposed guidance structure and gather input or case studies from the relevant teams. Done means analysts can find clear, confidence-building guidance for prompting, EES, code optimisation, and QA, including how AI should and should not be used.

Written by the indexing model from the issue text.