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 insightsengineering/nestdevs-tasks#121 to confirm the agreed CLAUDE.md structure and conventions for teal repositories. Then inspect this repository for relevant guidance to include and add CLAUDE.md at the repository root. Done means the file exists, follows the agreed structure, and contains applicable repository-specific information.

Written by the indexing model from the issue text.