ggml: Export GPU UUIDs

This enables matching up devices and information reported by the backend
with system management libraries such as nvml to get accurate free
memory reporting.

ml/backend.go

@@ -124,6 +124,10 @@ type DeviceMemory struct {
 	// may not be persistent across instances of the runner.
 	Name string
 
+	// UUID is a unique persistent identifier for the device for matching
+	// with system management libraries
+	UUID string
+
 	// Weights is the per-layer memory needed for the model weights.
 	Weights []Memory
 
@@ -152,6 +156,10 @@ func (m DeviceMemory) LogValue() slog.Value {
 		attrs = append(attrs, slog.Any("Graph", m.Graph))
 	}
 
+	if len(attrs) > 0 && m.UUID != "" {
+		attrs = append([]slog.Attr{slog.String("UUID", m.UUID)}, attrs...)
+	}
+
 	return slog.GroupValue(attrs...)
 }