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`