Clean, no-secrets walkthrough for getting a dev environment up. Covers
build, directory layout, commit conventions, what not to commit (key
files, .sparkle-keys, build artifacts), and common gotchas.
Complements docs/RELEASE-GUIDE.md which is admin-only and covers the
actual release flow + key management.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
