feat: Adds proposed kw interpolation.

Sources/Models/ProposedKWInterpolation.swift

@@ -0,0 +1,66 @@
+public enum ProposedKWInterpolation {
+  public struct Request: Codable, Equatable, Sendable {
+
+    public let elevation: Int?
+
+    // These are required if also doing a heat pump heating interpolation.
+    public let winterDesignTemperature: Int?
+    public let climateType: SystemType.ClimateType?
+    public let capacity: Capacity.HeatPumpHeating?
+
+    public let heatLoss: Int
+    public let proposedKW: Int
+
+    public init(
+      elevation: Int? = nil,
+      winterDesignTemperature: Int? = nil,
+      climateType: SystemType.ClimateType? = nil,
+      capacity: Capacity.HeatPumpHeating? = nil,
+      heatLoss: Int,
+      proposedKW: Int
+    ) {
+      self.elevation = elevation
+      self.winterDesignTemperature = winterDesignTemperature
+      self.climateType = climateType
+      self.capacity = capacity
+      self.heatLoss = heatLoss
+      self.proposedKW = proposedKW
+    }
+  }
+
+  public struct Response: Codable, Equatable, Sendable {
+
+    public let failed: Bool
+    public let failures: [String]?
+    public let supplementalHeatRequired: Int
+    public let capacityAsPercentOfLoad: Int
+    public let oversizingLimit: Int
+
+    // These are if a heat pump interpolation is also done.
+    public let altitudeAdjustmentMultiplier: Double?
+    public let balancePointTemperature: Int?
+    public let capacityAtDesign: Int?
+    public let finalCapacity: Capacity.HeatPumpHeating?
+
+    public init(
+      failures: [String]? = nil,
+      supplementalHeatRequired: Int,
+      capacityAsPercentOfLoad: Int,
+      oversizingLimit: Int,
+      altitudeAdjustmentMultiplier: Double? = nil,
+      balancePointTemperature: Int? = nil,
+      capacityAtDesign: Int? = nil,
+      finalCapacity: Capacity.HeatPumpHeating? = nil
+    ) {
+      self.failed = failures == nil ? false : !failures!.isEmpty
+      self.failures = failures
+      self.supplementalHeatRequired = supplementalHeatRequired
+      self.capacityAsPercentOfLoad = capacityAsPercentOfLoad
+      self.oversizingLimit = oversizingLimit
+      self.altitudeAdjustmentMultiplier = altitudeAdjustmentMultiplier
+      self.balancePointTemperature = balancePointTemperature
+      self.capacityAtDesign = capacityAtDesign
+      self.finalCapacity = finalCapacity
+    }
+  }
+}