Default build tool after "uv init --package"

[sha-huang]

At the set-up stage at the start of Day 1, after running

uv init --package

The pyproject.toml file has the [build-system] specified as:

[build-system]
requires = ["uv_build>=a.bb.cc,<d.ee"]
build-backend = "uv-build"

Understand this is the default after July 2025. With this setting, uv will still look for src/agent_code though the src directory has been removed. Hence, suggest either one of the following two changes to docs/day-01-hello-agent.md

1. When initiating the project, run
   uv init --package --build-backend hatchling

2. Manually modify the pyproject.toml content to:

[build-system]
requires = ["hatchling"]
build-backend = "hatchling.build"