Add Category entity, edit event tabs (info/categories/stats/settings), CRUD categories

- Create Category entity: name, position (sortable), event, startAt, endAt, isActive()
- Default endAt: event.startAt - 1 day
- Add 4 tabs on edit event page: Informations, Categories/Billets, Statistiques, Parametres
- Add routes: add category, delete category, reorder categories (JSON API)
- Categories sorted by position, drag handle for future Sortable.js
- Active/Inactive badge based on date range
- Add migration for category table

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

phpstan.neon

@@ -6,10 +6,11 @@ parameters:
         - src/Kernel.php
     ignoreErrors:
         -
-            message: '#Property App\\Entity\\(EmailTracking|MessengerLog|User|Payout|Event)::\$id .* never assigned#'
+            message: '#Property App\\Entity\\(EmailTracking|MessengerLog|User|Payout|Event|Category)::\$id .* never assigned#'
             paths:
                 - src/Entity/EmailTracking.php
                 - src/Entity/MessengerLog.php
                 - src/Entity/User.php
                 - src/Entity/Payout.php
                 - src/Entity/Event.php
+                - src/Entity/Category.php