* #396 New feature : match download status to files

* UI: Visible Books \> Set 'Downloaded' status automatically. Visible books. Prompts before saving changes
  * CLI: Full library. No prompt

Source/LibationCli/Options/SetDownloadStatusOptions.cs

@@ -0,0 +1,37 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+using ApplicationServices;
+using AudibleUtilities;
+using CommandLine;
+
+namespace LibationCli
+{
+    [Verb("set-status", HelpText = """
+        Set download statuses throughout library based on whether each book's audio file can be found. 
+        Must include at least one flag: --downloaded , --not-downloaded. 
+        Downloaded: If the audio file can be found, set download status to 'Downloaded'. 
+        Not Downloaded: If the audio file cannot be found, set download status to 'Not Downloaded'
+        """)]
+    public class SetDownloadStatusOptions : OptionsBase
+    {
+        [Option(shortName: 'd', longName: "downloaded", Required = true)]
+        public bool SetDownloaded { get; set; }
+
+        [Option(shortName: 'n', longName: "not-downloaded", Required = true)]
+        public bool SetNotDownloaded { get; set; }
+
+        protected override async Task ProcessAsync()
+        {
+            var libraryBooks = DbContexts.GetLibrary_Flat_NoTracking();
+
+            var bulkSetStatus = new BulkSetDownloadStatus(libraryBooks, SetDownloaded, SetNotDownloaded);
+            await Task.Run(() => bulkSetStatus.Discover());
+            bulkSetStatus.Execute();
+
+            foreach (var msg in bulkSetStatus.Messages)
+                Console.WriteLine(msg);
+        }
+    }
+}