Add debt system: track refunds/disputes, redirect payments until cleared

- Add nullable debt field to User entity with addDebt/reduceDebt helpers
- On refund webhook: add refunded amount to organizer debt
- On dispute webhook (charge.dispute.created): add disputed amount to debt
- OrderController: if organizer has debt > 0, payment goes to main Stripe
  account instead of connected account, debt reduced on payment success
- Display debt amount on organizer dashboard with warning message
- Add dispute notification email template
- Migration for debt column on user table

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

templates/account/index.html.twig

@@ -30,6 +30,16 @@
 
     {% else %}
 
+    {% if isOrganizer and app.user.debt is not null and app.user.debt > 0 %}
+    <div class="card-brutal-error p-6 mb-8">
+        <div class="flex items-center gap-3 mb-2">
+            <span class="text-2xl">&#9888;</span>
+            <h2 class="text-sm font-black uppercase tracking-widest text-red-800">Dette en cours</h2>
+        </div>
+        <p class="font-bold text-gray-700 text-sm">Suite a des remboursements ou litiges, votre compte presente une dette de <strong class="text-red-700">{{ (app.user.debt / 100)|number_format(2, ',', ' ') }} &euro;</strong>. Les paiements de vos clients seront retenus jusqu'a l'apurement complet de cette dette.</p>
+    </div>
+    {% endif %}
+
     {% if isOrganizer and app.user.billing and app.user.billingState != 'good' %}
     <div class="card-brutal-error p-8 text-center mb-8">
         <div class="text-4xl mb-4">&#9888;</div>

templates/email/dispute_created.html.twig

@@ -0,0 +1,13 @@
+{% extends 'email/base.html.twig' %}
+
+{% block title %}Litige recu{% endblock %}
+
+{% block content %}
+    <h2>Bonjour {{ firstName }},</h2>
+    <p>Un litige de <strong>{{ amount }} &euro;</strong> a ete ouvert sur la commande <strong>{{ orderNumber }}</strong>.</p>
+    <p>Ce montant a ete ajoute a votre dette. Les paiements de vos clients seront retenus jusqu'a l'apurement complet.</p>
+    <div style="background:#fef2f2;border-left:4px solid #dc2626;padding:12px 16px;margin:16px 0;">
+        <p style="font-weight:700;font-size:13px;color:#991b1b;margin:0;">Dette totale : {{ debt }} &euro;</p>
+    </div>
+    <p>Contactez <a href="mailto:contact@e-cosplay.fr">contact@e-cosplay.fr</a> pour toute question.</p>
+{% endblock %}