Ajoute le nouveau paquet server/ (architecture hexagonale : api,
domain, application, infrastructure/postgres, infrastructure/security,
migrations, scripts) avec un premier endpoint GET /health. dart pub
get OK, dart analyze clean, dart test 1/1 vert, serveur démarré
manuellement et validé (GET /health -> 200 {"status":"ok"}).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Migrations
PostgreSQL migrations will be added with the server persistence schema in ticket #49.