Get the status of a build by version.
Args: provider_id: Provider identifier. version: CalVer version string (YYYYMMDD.HHMMSS). service: Provider service for build operations.
Returns: BuildInfo with current build state.
Raises: HTTPException: 404 if build not found.
Successful Response
Build information exposed via API.
Excludes internal fields (image, cloud_build_id) that should not be exposed to users.