feat : MCP server infrastructure setup

Install symfony/mcp-bundle, add STDIO + HTTP transport config,
API token auth on User entity with custom authenticator and firewall,
generate-api-token console command, Nginx /_mcp location, fixture token.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

config/packages/security.yaml

@@ -28,6 +28,12 @@ security:
                 password_path: password
                 success_handler: lexik_jwt_authentication.handler.authentication_success
                 failure_handler: lexik_jwt_authentication.handler.authentication_failure
+        mcp:
+            pattern: ^/_mcp
+            stateless: true
+            provider: app_user_provider
+            custom_authenticators:
+                - App\Security\ApiTokenAuthenticator
         api:
             pattern: ^/api
             stateless: true
@@ -53,6 +59,7 @@ security:
         - { path: ^/api/docs, roles: PUBLIC_ACCESS }
         # Version de l'application en public
         - { path: ^/api/version, roles: PUBLIC_ACCESS, methods: [ GET ] }
+        - { path: ^/_mcp, roles: IS_AUTHENTICATED_FULLY }
         - { path: ^/api, roles: IS_AUTHENTICATED_FULLY }
 
 when@test: