Add export function

TempTrack/Storage/PersistentStorage.swift

@@ -2,6 +2,7 @@ import Foundation
 import Combine
 import BinaryCodable
 import SwiftUI
+import ZIPFoundation
 
 final class PersistentStorage: ObservableObject {
 
@@ -353,6 +354,34 @@ final class PersistentStorage: ObservableObject {
         defer { updateTransferCount() }
         return save(data: data, date: date, in: "transfers")
     }
+
+    // MARK: Export
+
+    private var zipArchive: URL {
+        FileManager.default.temporaryDirectory.appendingPathComponent("data.zip")
+    }
+
+    func createZip() throws -> URL {
+        // Define the destination zip file path
+        let archive = zipArchive
+
+        // Create the zip file
+        try FileManager.default.zipItem(
+            at: PersistentStorage.documentDirectory,
+            to: archive,
+            shouldKeepParent: false,
+            compressionMethod: .deflate)
+        return archive
+    }
+
+    func removeZipArchive() throws {
+        let archive = zipArchive
+        // Remove existing zip file if it exists
+        if FileManager.default.fileExists(atPath: archive.path) {
+            print("Removing archive file")
+            try FileManager.default.removeItem(at: archive)
+        }
+    }
 }
 
 private extension Array where Element == TemperatureMeasurement {