feat: Implement comprehensive architectural guidelines and clean code standards

- Establish feature-based architecture with clear separation between Logic, Data, and Shared layers
- Define directory structure conventions for controllers, entities, DTOs, managers, mappers, models, processors, providers, repositories, and services
- Implement Symfony 7.4+ compliance with proper Request handling (UI layer only)
- Enforce PHP 8+ attributes usage instead of annotations
- Set up proper DTO usage in UseCases with immutable properties
- Configure repository pattern with interfaces in Logic layer and implementations in Data layer
- Implement strict separation of concerns with UI layer handling Request objects exclusively
- Define clear naming conventions (PascalCase for feature names)
- Add shared components directory for reusable elements across features
- Establish HTTP status code constants usage instead of magic numbers
- Configure proper file placement for controllers in UI/Frontend, UI/Api, and UI/CLI subdirectories
- Enforce modern PHP practices with explicit return types and strict typing

This commit lays the foundation for a maintainable, scalable Symfony 7.4+ application following clean architecture principles and modern coding standards.

.continue/rules/symfony-dto-validation-strategy.md

@@ -0,0 +1,11 @@
+---
+globs: "**/UI/**/*.php, **/Logic/**/DTO/*.php"
+description: Defines the standard for input validation in Symfony 7 projects.
+  Logic layer DTOs hold the validation rules via attributes. The UI layer is
+  responsible for executing the validation using the injected validator service,
+  ensuring clean separation of concerns and preventing invalid data from
+  entering the business logic.
+alwaysApply: false
+---
+
+All input validation must be performed on DTOs located in /src/Logic/[FeatureName]/DTO using PHP 8 #[Assert\...] attributes. Controllers in the UI layer (/src/UI/...) must inject Symfony\Component\Validator\Validator\ValidatorInterface, validate the DTO before passing it to UseCases, and handle validation errors immediately.