ver. 0.284: DbModel elimination, update packages for 0.283-0.284

- Removed class.DbModel.php — only consumer (shop\Promotion) now has
  inlined constructor + __get()
- Created update packages: ver_0.283.zip (S→Helpers migration, ~130 files),
  ver_0.284.zip (DbModel removal)
- Updated docs: CHANGELOG, PROJECT_STRUCTURE, FRONTEND_REFACTORING_PLAN

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

autoload/shop/class.Promotion.php

@@ -1,11 +1,9 @@
 <?php
 namespace shop;
 
-use DbModel;
-
-class Promotion extends DbModel
+class Promotion
 {
-  public $table = 'pp_shop_promotion';
+  private $data = [];
 
   public static $condition_type = [
     1 => 'Rabat procentowy na produkty z kategorii 1 jeżeli w koszyku jest produkt z kategorii 2',
@@ -17,6 +15,25 @@ class Promotion extends DbModel
 
   public static $discount_type = [ 1 => 'Rabat procentowy' ];
 
+  public function __construct( $id )
+  {
+    global $mdb;
+
+    if ( $id )
+    {
+      $result = $mdb->get( 'pp_shop_promotion', '*', [ 'id' => $id ] );
+      if ( is_array( $result ) )
+        $this->data = $result;
+    }
+  }
+
+  public function __get( $variable )
+  {
+    if ( isset( $this->data[$variable] ) )
+      return $this->data[$variable];
+    return null;
+  }
+
   public static function get_active_promotions()
   {
     global $mdb;