Persist keys to db. Necessary in the event that download succeeds then decrypt fails.

ApplicationServices/LibraryCommands.cs

@@ -119,5 +119,13 @@ namespace ApplicationServices
 				throw;
 			}
 		}
+
+		// I hate how unintuitive this is to use/remember. Will hopefully be cleaned up in a future comprehensive data strategy overhaul
+		public static void UpdateBook(Book book)
+		{
+			using var context = DbContexts.GetContext();
+			context.Update(book);
+			context.SaveChanges();
+		}
 	}
 }