Defined the AuthTransport enumeration in the library target.

Sources/DiscogsService/Public/Enumerations/AuthTransport.swift

@@ -0,0 +1,33 @@
+// ===----------------------------------------------------------------------===
+//
+// This source file is part of the DiscogsService open source project
+//
+// Copyright (c) 2025 Röck+Cöde VoF. and the DiscogsService project authors
+// Licensed under Apache license v2.0
+//
+// See LICENSE for license information
+// See CONTRIBUTORS for the list of DiscogsService project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+// ===----------------------------------------------------------------------===
+
+/// A representation of the available transport options to send credentials in authenticated requests.
+public enum AuthTransport {
+    /// Authentication credential are sent in a request as an `Authentication` header.
+    ///
+    /// This means that the header will be added to any existing header in a request, like this:
+    /// ```bash
+    /// curl "https://api.discogs.com/database/search?q=Slayer" -H "Authorization: Discogs key=foo123, secret=bar456"
+    /// curl "https://api.discogs.com/database/search?q=Slayer" -H "Authorization: Discogs token=abcxyz123456"
+    /// ```
+    case onHeader
+    /// Authentication credential are sent in a request as parameters in the query string.
+    ///
+    /// This means that the parameters will be injected into the query in a request, like this:
+    /// ```bash
+    /// curl "https://api.discogs.com/database/search?q=Slayer&key=foo123&secret=bar456"
+    /// curl "https://api.discogs.com/database/search?q=Slayer&token=abcxyz123456"
+    /// ```
+    case onQuery
+}