feat: Setup projet Classeo avec infrastructure Docker et architecture DDD

Configure l'environnement de développement complet avec Docker Compose,
structure DDD 4 Bounded Contexts, et pipeline CI/CD GitHub Actions.

Corrections compatibilité CI:
- Symfony 8 nécessite monolog-bundle ^4.0 (la v3.x ne supporte que jusqu'à Symfony 7)
- ESLint v9 nécessite flat config (eslint.config.js) - le format .eslintrc.cjs est obsolète

backend/config/packages/security.yaml

@@ -0,0 +1,41 @@
+security:
+    # https://symfony.com/doc/current/security.html#registering-the-user-hashing-passwords
+    password_hashers:
+        Symfony\Component\Security\Core\User\PasswordAuthenticatedUserInterface: 'auto'
+
+    # https://symfony.com/doc/current/security.html#loading-the-user-the-user-provider
+    providers:
+        # used to reload user from session & other features (e.g. switch_user)
+        # Configure user provider when User entity is created
+        users_in_memory:
+            memory:
+                users:
+                    admin: { password: 'admin', roles: ['ROLE_ADMIN'] }
+
+    firewalls:
+        dev:
+            pattern: ^/(_(profiler|wdt)|css|images|js)/
+            security: false
+        api:
+            pattern: ^/api
+            stateless: true
+            jwt: ~
+        main:
+            lazy: true
+            provider: users_in_memory
+
+    # Easy way to control access for large sections of your site
+    # Note: Only the *first* access control that matches will be used
+    access_control:
+        - { path: ^/api/docs, roles: PUBLIC_ACCESS }
+        - { path: ^/api/login, roles: PUBLIC_ACCESS }
+        - { path: ^/api, roles: IS_AUTHENTICATED_FULLY }
+
+when@test:
+    security:
+        password_hashers:
+            Symfony\Component\Security\Core\User\PasswordAuthenticatedUserInterface:
+                algorithm: auto
+                cost: 4 # Lowest possible value for bcrypt
+                time_cost: 3 # Lowest possible value for argon
+                memory_cost: 10 # Lowest possible value for argon