Phase 0 : entités, migrations, API Platform, PostGIS

- API Platform + Doctrine ORM + jsor/doctrine-postgis installés
- 6 entités Symfony (SargassumObservation, SargassumForecast,
  DataIngestionJob, CoastalPoint, ImpactScore, UserFeedback)
- Migration initiale manuelle avec CREATE EXTENSION postgis,
  toutes les tables, index GIST et BTREE
- doctrine.yaml configuré pour PostgreSQL 16 + types PostGIS
- Roadmap Phase 0 complète

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/config/bundles.php

@@ -2,4 +2,10 @@
 
 return [
     Symfony\Bundle\FrameworkBundle\FrameworkBundle::class => ['all' => true],
+    Symfony\Bundle\TwigBundle\TwigBundle::class => ['all' => true],
+    Symfony\Bundle\SecurityBundle\SecurityBundle::class => ['all' => true],
+    Doctrine\Bundle\DoctrineBundle\DoctrineBundle::class => ['all' => true],
+    Doctrine\Bundle\MigrationsBundle\DoctrineMigrationsBundle::class => ['all' => true],
+    Nelmio\CorsBundle\NelmioCorsBundle::class => ['all' => true],
+    ApiPlatform\Symfony\Bundle\ApiPlatformBundle::class => ['all' => true],
 ];