feat: Starts manual-d client and adds friction rate calculation and tests.

Tests/ManualDClientTests/ManualDClientTests.swift

@@ -0,0 +1,45 @@
+import Dependencies
+import Foundation
+import ManualDClient
+import ManualDCore
+import Testing
+
+@Suite("ManualDClient Tests")
+struct ManualDClientTests {
+
+  var numberFormatter: NumberFormatter {
+    let formatter = NumberFormatter()
+    formatter.minimumFractionDigits = 2
+    formatter.maximumFractionDigits = 2
+    formatter.roundingMode = .halfUp
+    return formatter
+  }
+
+  @Test
+  func frictionRate() async throws {
+    let manualD = ManualDClient.liveValue
+    let response = try await manualD.frictionRate(
+      .init(
+        externalStaticPressure: 0.5,
+        componentPressureLosses: .mock,
+        totalEffectiveLength: 185
+      )
+    )
+    #expect(numberFormatter.string(for: response.availableStaticPressure) == "0.11")
+    #expect(numberFormatter.string(for: response.frictionRate) == "0.06")
+  }
+
+  @Test
+  func frictionRateFails() async throws {
+    await #expect(throws: ManualDError.self) {
+      let manualD = ManualDClient.liveValue
+      _ = try await manualD.frictionRate(
+        .init(
+          externalStaticPressure: 0.5,
+          componentPressureLosses: .mock,
+          totalEffectiveLength: 0
+        )
+      )
+    }
+  }
+}