Add configuration for cron key and document code style conventions

- Added cron key to config.php for scheduled tasks.
- Created code_style_and_conventions.md to outline PHP version, file naming, DI pattern, controller wiring, Medoo ORM pitfalls, test conventions, caching, and database structure.
- Added project_overview.md detailing the purpose, tech stack, architecture, entry points, and key classes of the shopPRO project.
- Introduced suggested_commands.md for testing and system utilities commands.
- Added task_completion_checklist.md for a structured approach to completing tasks.
- Included .DS_Store files in autoload and templates directories for macOS compatibility.

.serena/memories/code_style_and_conventions.md

@@ -0,0 +1,47 @@
+# Code Style and Conventions
+
+## PHP Version
+PHP 7.4 — no PHP 8.0+ features allowed.
+
+## File Naming
+- New classes: `ClassName.php` (no prefix)
+- Legacy classes: `class.ClassName.php` (leave until migrated)
+
+## DI Pattern (all new code)
+```php
+class ExampleRepository {
+    private $db;
+    public function __construct($db) {
+        $this->db = $db;
+    }
+    public function find(int $id): ?array {
+        return $this->db->get('pp_table', '*', ['id' => $id]);
+    }
+}
+```
+
+## Controller Wiring
+- Admin: `admin\App::getControllerFactories()`
+- Frontend: `front\App::getControllerFactories()`
+- API: `api\ApiRouter::getControllerFactories()`
+
+## Medoo ORM Pitfalls
+- `$mdb->delete($table, $where)` takes 2 arguments, NOT 3
+- `$mdb->get()` returns `null` when no record, NOT `false`
+- After `$mdb->insert()`, check `$mdb->id()` to confirm success
+
+## Test Conventions
+- Extend `PHPUnit\Framework\TestCase`
+- Mock Medoo: `$this->createMock(\medoo::class)`
+- AAA pattern: Arrange, Act, Assert
+- Mirror source structure: `tests/Unit/Domain/{Module}/{Class}Test.php`
+
+## Caching
+- Redis via `\Shared\Cache\CacheHandler`
+- Key pattern: `shop\product:{id}:{lang}:{permutation_hash}`
+- Default TTL: 86400 (24h)
+- Data serialized — use `unserialize()` after `get()`
+
+## Database
+- Table prefix: `pp_`
+- Key tables: `pp_shop_products`, `pp_shop_orders`, `pp_shop_categories`, `pp_shop_clients`