fix live passport service macOS build

Narrow the live service initializer visibility, correct key material decoding, and restrict the location evidence helper to iOS so the app builds cleanly on macOS.

swift/Sources/Core/Services/MockIDPService.swift

@@ -34,7 +34,7 @@ actor LiveIDPService: IDPServicing {
     private let appStateStore: AppStateStoring
     private let keyStore: PassportKeyStoring
 
-    init(
+    private init(
         appStateStore: AppStateStoring = UserDefaultsAppStateStore(),
         keyStore: PassportKeyStoring = DefaultPassportKeyStore()
     ) {
@@ -54,7 +54,10 @@ actor LiveIDPService: IDPServicing {
         let client = LiveTypedRequestClient(baseURL: baseURL)
         let keyMaterial = try loadOrCreateKeyMaterial(for: context.originHost)
         let signingPayload = try buildEnrollmentSigningPayload(from: context)
-        let signatureBase64 = try signPayload(signingPayload, with: keyMaterial.privateKeyData)
+        guard let privateKeyData = Data(base64Encoded: keyMaterial.privateKeyBase64) else {
+            throw AppError.invalidPairingPayload
+        }
+        let signatureBase64 = try signPayload(signingPayload, with: privateKeyData)
 
         let enrollmentResponse = try await client.fire(
             method: "completePassportEnrollment",
@@ -1134,7 +1137,7 @@ private struct ServerAlert: Decodable {
     let data: DataPayload
 }
 
-#if canImport(CoreLocation)
+#if canImport(CoreLocation) && os(iOS)
 @MainActor
 private final class CurrentLocationEvidenceProvider: NSObject, @preconcurrency CLLocationManagerDelegate {
     private var manager: CLLocationManager?