fix(fm): keep the requested name of a partner-hosted instance

SRM hands FM the whole deploy command, instance_name included, when the
target zone belongs to a partner. FM dropped the name and answered
/internal/federated-service-instances with ref "federated:<id>", so the
portal listed every partner-hosted instance by its UUID.

Keep instance_name in the InstallApp transaction summary and return it
as ref, falling back to the instance id: the same rule SRM applies to a
local instance. The summary is JSON already, so no migration.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>