Add README Quickstart with prerequisites; update author email

- README: add a 5-minute Quickstart with a Python 3.9+ prerequisites
  block (OS-specific python3/pip notes + venv step for PEP-668 systems)
- pyproject: set author email to david.boyd1@dc.gov

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

pyproject.toml

@@ -9,7 +9,7 @@ description = "Dependency-light Python client for the U.S. Bureau of Labor Stati
 readme = "README.md"
 requires-python = ">=3.9"
 license = { text = "MIT" }
-authors = [{ name = "Dave Boyd", email = "dave@tiggr.org" }]
+authors = [{ name = "Dave Boyd", email = "david.boyd1@dc.gov" }]
 keywords = ["bls", "economics", "labor-statistics", "cpi", "jolts", "unemployment", "wages"]
 dependencies = ["requests>=2.28"]