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.

config.php

@@ -17,4 +17,6 @@ $config['debug']['apilo'] = true;
 
 $config['trustmate']['enabled'] = true;
 $config['trustmate']['uid'] = '34eb36ba-c715-4cdc-8707-22376c9f14c7';
+
+$config['cron_key'] = 'Gi7FzWtkry19hZ1BqT1LKEWfwokQpigh';
 ?>