feat: quiz page question rework (#181)

- Replace Bootstrap accordion with flat card list for questions
- Add HTML5 drag-and-drop reordering with placeholder-between-cards UX
  and amber/green/red save status indicator next to the heading
- Add edit button per question opening a Bootstrap modal (bo--modal-form
  Stimulus controller with X-Modal-Request header pattern)
- Show read-only view button instead of edit for locked/finalized quizzes
- Add BankQuestion edit modal in question bank tab using same infrastructure
- Move modal action buttons into modal-footer via <template data-modal-footer>
- Fix IS_AUTHENTICATED_FULLY 403: replace ROLE_USER with IS_AUTHENTICATED
  on all backoffice controllers and in security.yaml access_control

config/packages/security.yaml

@@ -30,7 +30,7 @@ security:
 
     access_control:
         - { path: ^/admin, roles: ROLE_ADMIN }
-        - { path: ^/backoffice, roles: ROLE_USER }
+        - { path: ^/backoffice, roles: IS_AUTHENTICATED }
 
 when@test:
     security: