unit type getters for volumetric flow rate and energy density

lib/src/units/energy_density/energy_density_unit.dart

@@ -58,6 +58,15 @@ enum EnergyDensityUnit implements LinearUnit<EnergyDensityUnit> {
   @override
   final String symbol;
 
+  /// Returns `true` only for [joulePerCubicMeter], the SI derived unit of energy density.
+  @override
+  bool get isSI => this == EnergyDensityUnit.joulePerCubicMeter;
+
+  /// Returns `true` for all units, since every `EnergyDensityUnit` member is
+  /// a decimal metric unit.
+  @override
+  bool get isMetric => true;
+
   // --- Pre-calculated direct conversion factors ---
   final double _factorToJoulePerCubicMeter;
   final double _factorToJoulePerLiter;

lib/src/units/volumetric_flow_rate/volumetric_flow_rate_unit.dart

@@ -70,6 +70,22 @@ enum VolumetricFlowRateUnit implements LinearUnit<VolumetricFlowRateUnit> {
   @override
   final String symbol;
 
+  /// Returns `true` only for [cubicMeterPerSecond], the SI derived unit of volumetric flow rate.
+  @override
+  bool get isSI => this == VolumetricFlowRateUnit.cubicMeterPerSecond;
+
+  /// Returns `false` for the imperial/US customary [cubicFootPerSecond],
+  /// [cubicFootPerMinute], [gallonPerMinute], and [gallonPerHour]; `true`
+  /// for all decimal metric cubic-meter- and liter-based units.
+  @override
+  bool get isMetric => switch (this) {
+    VolumetricFlowRateUnit.cubicFootPerSecond ||
+    VolumetricFlowRateUnit.cubicFootPerMinute ||
+    VolumetricFlowRateUnit.gallonPerMinute ||
+    VolumetricFlowRateUnit.gallonPerHour => false,
+    _ => true,
+  };
+
   // --- Pre-calculated direct conversion factors from this unit to all others ---
   final double _factorToCubicMeterPerSecond;
   final double _factorToCubicMeterPerMinute;