feat: open-source 小浣熊阅读 for iOS

Sources/LegadoCore/Import/QRCodeDecoder.swift

@@ -0,0 +1,13 @@
+import Foundation
+import Vision
+
+public struct QRCodeDecoder: Sendable {
+    public init() {}
+    public func detect(in data: Data) throws -> [String] {
+        let request = VNDetectBarcodesRequest()
+        request.symbologies = [.qr]
+        try VNImageRequestHandler(data: data).perform([request])
+        var seen = Set<String>()
+        return (request.results ?? []).compactMap(\.payloadStringValue).filter { seen.insert($0).inserted }
+    }
+}