feat: Adds psychrometrics calculator.

Sources/ApiController/Extensions/Psychrometrics.swift

@@ -0,0 +1,36 @@
+import Dependencies
+import Logging
+import PsychrometricClient
+import Routes
+
+public extension Routes.Psychrometrics.Request {
+
+  func respond(logger: Logger) async throws -> Psychrometrics.Response {
+    @Dependency(\.psychrometricClient) var psychrometricClient
+    try validate()
+    let properties = try await psychrometricClient.psychrometricProperties(
+      .dryBulb(.fahrenheit(temperature), relativeHumidity: humidity%, altitude: .feet(altitude ?? 0))
+    )
+    var warnings = [String]()
+    if altitude == nil || altitude == 0 {
+      warnings.append(
+        "Calculations based on altitude of sea level - set project altitude for higher accuracy."
+      )
+    }
+
+    return .init(properties: properties, warnings: warnings)
+  }
+
+  private func validate() throws {
+    guard temperature > 0 else {
+      throw ValidationError(message: "Temperature should be greater than 0.")
+    }
+    guard humidity > 0, humidity <= 100 else {
+      throw ValidationError(message: "Relative humidity should be greater than 0 and less than or equal to 100.")
+    }
+    if let altitude, altitude < 0 {
+      throw ValidationError(message: "Altitude should be greater than 0.")
+    }
+  }
+
+}