Add `CLAUDE.md`

## Description

Add a `CLAUDE.md` file to this repository to provide repository-specific context and guidance when working with Claude Code.

The structure and expected content for `CLAUDE.md` are being defined in insightsengineering/nestdevs-tasks#121. The implementation should follow the agreed structure from that issue and adapt the content to this repository.

The `CLAUDE.md` should capture the relevant repository-specific information while following the common conventions agreed for the teal repositories.

## Acceptance criteria

* `CLAUDE.md` is added to the repository.
* The file follows the structure agreed in insightsengineering/nestdevs-tasks#121.
* Repository-specific guidance is included where relevant.

Start by reading the agreed structure in insightsengineering/nestdevs-tasks#121, then inspect this repository for the project-specific context needed in CLAUDE.md. Add the file using the common teal repository conventions and include relevant guidance for this repository. Done means CLAUDE.md exists, follows the agreed structure, and contains repository-specific information where relevant.

Written by the indexing model from the issue text.