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>

migrations/Version20260320214602.php

@@ -0,0 +1,34 @@
+<?php
+
+declare(strict_types=1);
+
+namespace DoctrineMigrations;
+
+use Doctrine\DBAL\Schema\Schema;
+use Doctrine\Migrations\AbstractMigration;
+
+/**
+ * Auto-generated Migration: Please modify to your needs!
+ */
+final class Version20260320214602 extends AbstractMigration
+{
+    public function getDescription(): string
+    {
+        return '';
+    }
+
+    public function up(Schema $schema): void
+    {
+        // this up() migration is auto-generated, please modify it to your needs
+        $this->addSql('CREATE TABLE category (id INT GENERATED BY DEFAULT AS IDENTITY NOT NULL, name VARCHAR(255) NOT NULL, position INT NOT NULL, start_at TIMESTAMP(0) WITHOUT TIME ZONE NOT NULL, end_at TIMESTAMP(0) WITHOUT TIME ZONE NOT NULL, created_at TIMESTAMP(0) WITHOUT TIME ZONE NOT NULL, event_id INT NOT NULL, PRIMARY KEY (id))');
+        $this->addSql('CREATE INDEX IDX_64C19C171F7E88B ON category (event_id)');
+        $this->addSql('ALTER TABLE category ADD CONSTRAINT FK_64C19C171F7E88B FOREIGN KEY (event_id) REFERENCES event (id) ON DELETE CASCADE NOT DEFERRABLE');
+    }
+
+    public function down(Schema $schema): void
+    {
+        // this down() migration is auto-generated, please modify it to your needs
+        $this->addSql('ALTER TABLE category DROP CONSTRAINT FK_64C19C171F7E88B');
+        $this->addSql('DROP TABLE category');
+    }
+}