The server role migration gives every normal server the combined role, and
the build server queries counted combined servers as build servers.
"Use a build server" then built on a random production server, the resource
picker listed each server twice, and "Deployments only" did not stop builds.
- Build server selection and the picker use only "Builds only" servers.
A null role falls back to the legacy is_build_server flag.
- Without a dedicated build server, builds fall back to the deployment
server, never to another combined server.
- A "Deployments only" server always builds on a build server and needs a
Docker image name. It never builds itself, except for restarts. Docker
image and Compose applications are not affected.
- Setting "Deployments only" requires a dedicated build server.
- The API keeps is_build_server in sync with the role for downgrades.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Add feature coverage for updating a server from private_key_uuid, rejecting unknown or cross-team private keys, and preserving the existing key when the field is omitted.