docs: add CLAUDE.md project reference documentation

CLAUDE.md

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+# CLAUDE.md - Abiball Project Reference
+
+## Commands
+- Setup: `composer install`
+- Run server: `symfony server:start` or `php -S localhost:8000 -t public/`
+- Clear cache: `bin/console cache:clear`
+- Build assets: `bin/console importmap:install`
+- Compile Tailwind: `bin/console tailwind:build` and `bin/console tailwind:build --watch`
+- Run specific test: `bin/phpunit tests/path/to/TestFile.php`
+- Database migrations: `bin/console doctrine:migrations:migrate`
+
+## Code Style
+- PHP >= 8.2, Symfony 7.2
+- PSR-4 autoloading (`App\` namespace in `src/`)
+- Use strict typing (`declare(strict_types=1)`)
+- Controllers in `src/Controller/` with suffix `Controller`
+- Entities in `src/Entity/` with repositories in `src/Repository/`
+- Forms in `src/Form/` with suffix `Type`
+- Services in `src/Service/` with dependency injection
+- Use Symfony data objects for form handling
+- Twig templates in `templates/` with directories matching controller names
+- JavaScript in `assets/` with Stimulus controllers for dynamic components
+- CSS using Tailwind utility classes
+
+## Error Handling
+- Use appropriate Symfony exceptions
+- Handle form submissions with proper validation
+- Use flasher-noty for user notifications