Source-build docs omit uv required by just fmt

What happened?

docs/install.md tells contributors building from source to install Rust, just, and cargo-nextest, then recommends running the root justfile helpers such as just fmt.

However, the fmt recipe in the root justfile also runs Python SDK formatting through uv:

uv run --frozen --project ../sdk/python --extra dev ruff check --fix --fix-only ../sdk/python
uv run --frozen --project ../sdk/python --extra dev ruff format ../sdk/python

A fresh source-build setup following docs/install.md may therefore fail at just fmt unless uv is installed separately.

Expected behavior

The source-build docs should either include uv in the helper tool installation steps or clarify that uv is required only when running formatting checks that touch the Python SDK.

Additional context

I searched open issues and PRs for terms including uv, just fmt, and install docs, and did not find an existing open item that appears to cover this setup-doc omission.