feat: Adds heat pump heating interpolation.

Sources/Models/HeatPumpHeatingInterpolation.swift

@@ -0,0 +1,47 @@
+public enum HeatPumpHeatingInterpolation {
+  public struct Request: Codable, Equatable, Sendable {
+
+    public let elevation: Int?
+    public let winterDesignTemperature: Int
+    public let heatLoss: Int
+    public let climateType: SystemType.ClimateType
+    public let capacity: Capacity.HeatPumpHeating
+
+    public init(
+      elevation: Int? = nil,
+      winterDesignTemperature: Int,
+      heatLoss: Int,
+      climateType: SystemType.ClimateType,
+      capacity: Capacity.HeatPumpHeating
+    ) {
+      self.elevation = elevation
+      self.winterDesignTemperature = winterDesignTemperature
+      self.heatLoss = heatLoss
+      self.climateType = climateType
+      self.capacity = capacity
+    }
+  }
+
+  public struct Response: Codable, Equatable, Sendable {
+
+    public let altitudeAdjustmentMultiplier: Double?
+    public let balancePointTemperature: Int
+    public let capacityAtDesign: Int
+    public let finalCapacity: Capacity.HeatPumpHeating
+    public let supplementalHeatRequired: Int
+
+    public init(
+      altitudeAdjustmentMultiplier: Double? = nil,
+      balancePointTemperature: Int,
+      capacityAtDesign: Int,
+      finalCapacity: Capacity.HeatPumpHeating,
+      supplementalHeatRequired: Int
+    ) {
+      self.altitudeAdjustmentMultiplier = altitudeAdjustmentMultiplier
+      self.balancePointTemperature = balancePointTemperature
+      self.capacityAtDesign = capacityAtDesign
+      self.finalCapacity = finalCapacity
+      self.supplementalHeatRequired = supplementalHeatRequired
+    }
+  }
+}