The build.gradle now reads RELEASE_STORE_FILE, RELEASE_STORE_PASSWORD,
RELEASE_KEY_ALIAS, and RELEASE_KEY_PASSWORD env vars for release signing.
Falls back to debug keystore for local development.
Also updates whatsnew for v0.4.1.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>