Documented the ISOTimestampTranscoder transcoder in the library target.

Sources/Internal/Transcoders/ISOTimestampTranscoder.swift

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+//===----------------------------------------------------------------------===
+//
+// This source file is part of the AmiiboService open source project
+//
+// Copyright (c) 2024-2025 Röck+Cöde VoF. and the AmiiboAPI project authors
+// Licensed under the EUPL 1.2 or later.
+//
+// See LICENSE for license information
+// See CONTRIBUTORS for the list of AmiiboAPI project authors
+//
+//===----------------------------------------------------------------------===
+
+import Foundation
+import OpenAPIRuntime
+
+/// A type that allows the decoding and encoding of ISO timestamp dates, defined by the `yyyy-MM-dd'T'HH:mm:ss.SSSSSS` custom date format.
+struct ISOTimestampTranscoder {
+    
+    // MARK: Properties
+
+    private let dateFormatter: DateFormatter = .isoTimestamp
+    
+}
+
+ // MARK: - DateTranscoder
+
+extension ISOTimestampTranscoder: DateTranscoder {
+    
+    // MARK: Functions
+    
+    func encode(_ date: Date) throws -> String {
+        dateFormatter.string(from: date)
+    }
+    
+    func decode(_ string: String) throws -> Date {
+        dateFormatter.date(from: string) ?? .init()
+    }
+    
+}