Add admin panel, Meilisearch buyer search, email redesign, and multiple features

Admin panel (/admin, ROLE_ROOT):
- Dashboard with CA HT Global/Commission cards and Meilisearch sync button
- Buyers page with search (Meilisearch), create form, pagination (KnpPaginator)
- Buyer actions: resend verification, force verify, reset password, delete
- Organizers page with tabs (pending/approved), approve/reject with emails
- Neo-brutalist design matching main site theme
- Vite admin entry point with dedicated SCSS
- CSP-compatible confirm dialogs via data-confirm attributes

Meilisearch integration:
- Auto-index buyers on email verification
- Remove from index on buyer deletion
- Manual sync button on dashboard
- Search bar on buyers page
- Add Meilisearch service to CI/SonarQube workflows
- Add MEILISEARCH env vars to .env.test
- Fix MeilisearchMessageHandler infinite loop: use request() directly instead
  of service methods that re-dispatch messages

Email templates:
- Redesign base email template to neo-brutalist style (borders, shadows, yellow footer)
- Add E-Cosplay logo, "E-Ticket solution proposee par e-cosplay.fr"
- Add admin_reset_password, organizer_approved, organizer_rejected templates

Other:
- Install knplabs/knp-paginator-bundle
- Add ^/admin access_control for ROLE_ROOT in security.yaml
- Update site footer with E-Ticket branding
- 18 admin tests, updated MeilisearchMessageHandler tests

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

composer.json

@@ -12,6 +12,7 @@
         "doctrine/orm": "^3.6",
         "dompdf/dompdf": "*",
         "endroid/qr-code-bundle": "*",
+        "knplabs/knp-paginator-bundle": "^6.10",
         "knpuniversity/oauth2-client-bundle": "^2.20",
         "league/flysystem-aws-s3-v3": "^3.32",
         "league/flysystem-bundle": "^3.6",