Stores Impact request context on the current OpenTelemetry baggage so that the canonical impact.context.<key> attributes ride with the OTel context across process boundaries (GenServer calls, Tasks, anywhere OpenTelemetry.Ctx.attach/1 is used).

Reserved canonical keys: :user_id, :interaction_id, :version_id. Any additional keys passed via :attributes are flattened under impact.context.<key>.

Why baggage and not Process dict

Process dictionaries are local to one BEAM process. The agent loop in a GenServer is a different process from the LiveView / controller that started the trace, so storing context in Process.put/2 would only attach it to spans created at the call site, not to spans created in the GenServer. OTel baggage is part of the OTel context and propagates automatically when the caller passes the context across the boundary.