Replace `pip` with `uv pip`

For the devcontainer: We should use [`uv pip`](https://docs.astral.sh/uv/pip/compatibility/) instead of `pip` because it is faster.

## Acceptance Criteria
- Devcontainer build installs dependencies using `uv pip` instead of `pip`
- `uv pip` is aliased to `pip` for backwards-compatibility (or we agree to do a breaking change)
- Devcontainer build is manually tested
- Devcontainer build is timed compared to `main`

Start with the repository's devcontainer configuration and identify where dependencies are currently installed with pip. Compare the build with main, then verify that the build uses uv pip, check the backward-compatibility decision, and manually time the result against main.

Rédigé par le modèle d'indexation à partir du texte de l'issue.