Add new fields to items: id_code, image, location; implement QR code generation and printing; update translations and UI

add_columns.php

@@ -0,0 +1,8 @@
+<?php
+require 'vendor/autoload.php';
+require 'config.php';
+ = new PDO('sqlite:' . DB_PATH);
+->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
+try {
+    ->exec('ALTER TABLE items ADD COLUMN id_code TEXT');
+    echo id_code