v1.6.0

Adds .ddev/rdg-native, an explicit opt-out from derived mode.

Mode detection keyed purely off the presence of .platform.app.yaml, which cannot tell config we deploy from apart from config somebody left behind. Repos carrying one from an abandoned Platform.sh evaluation — no .platform/local/project.yaml, and an AWS devops/buildspec.yml instead — landed in derived mode, where the pre-start guard aborts every start until someone runs ddev rdg-sync, which then derives PHP and database versions from a file nobody deploys from.

touch .ddev/rdg-native      # and commit it

The marker beats every other signal, RDG_APP_ROOT included: it is committed and describes the repo, where the variable is a per-shell override.

A file rather than a config key because the guard runs on the host while the project may be stopped, so it can read neither web_environment nor yq.