fix: durcir les filtres AFAI — SWIR guard, NDWI marge côtière, filtre PostGIS 1km²

- S2 : ajout garde SWIR (B11 > 0.03 = artifact atmo/cirrus), NIR abaissé
  à 0.06, NDWI marge côtière (> 0.05), AFAI threshold 0.020
- S3 : même logique, NIR 0.06, NDWI 0.05, MCI 0.020
- PostGIS : suppression des polygones < 1 km² après vectorisation
  (résidus ponctuels = bruit ou artefact atmosphérique en Caraïbe)
- Auto-suppression de l'observation si plus aucun polygone valide
- PROCESSING_VERSION 1.2.0

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

backend/src/Service/Ingestion/IngestionService.php

@@ -18,7 +18,7 @@ class IngestionService
     private const SARGASSUM_DN        = 1;
     private const SIMPLIFY_TOLERANCE  = 0.001; // degrés (~100m à l'équateur)
     private const MIN_RING_POINTS     = 8;     // filtre polygones < ~2 pixels (bruit)
-    private const PROCESSING_VERSION  = '1.1.0';
+    private const PROCESSING_VERSION  = '1.2.0';
 
     public function __construct(
         private SentinelHubClient $sentinelHub,
@@ -218,17 +218,46 @@ class IngestionService
         return ['type' => 'MultiPolygon', 'coordinates' => $polygons];
     }
 
+    private const MIN_POLYGON_AREA_M2 = 1_000_000; // 1 km² — filtre résidus AFAI
+
     private function updateSpatialMeta(string $id): void
     {
+        // 1) Filtrer les micro-polygones < MIN_POLYGON_AREA_M2 avant simplification
+        //    Un fragment < 1 km² en plein océan est du bruit ou un artefact atmo.
+        $this->em->getConnection()->executeStatement(
+            "UPDATE sargassum_observation
+             SET geometry = (
+                SELECT COALESCE(
+                    ST_Collect(geom),
+                    'GEOMETRYCOLLECTION EMPTY'::geometry
+                )
+                FROM (
+                    SELECT (ST_Dump(geometry)).geom AS geom
+                ) parts
+                WHERE ST_Area(geom::geography) >= :minArea
+             )
+             WHERE id = :id",
+            ['id' => $id, 'minArea' => self::MIN_POLYGON_AREA_M2]
+        );
+
+        // 2) Simplifier + calculer bbox et surface finale
         $this->em->getConnection()->executeStatement(
             'UPDATE sargassum_observation
              SET
-                geometry     = ST_SimplifyPreserveTopology(geometry, :tolerance),
-                bbox         = ST_Envelope(geometry),
+                geometry      = ST_SimplifyPreserveTopology(geometry, :tolerance),
+                bbox          = ST_Envelope(geometry),
                 coverage_area = ROUND(CAST(ST_Area(geometry::geography) / 1000000 AS numeric), 2)
-             WHERE id = :id',
+             WHERE id = :id
+               AND NOT ST_IsEmpty(geometry)',
             ['id' => $id, 'tolerance' => self::SIMPLIFY_TOLERANCE]
         );
+
+        // 3) Supprimer l'observation si plus rien ne reste après filtrage
+        $this->em->getConnection()->executeStatement(
+            'DELETE FROM sargassum_observation
+             WHERE id = :id AND (ST_IsEmpty(geometry) OR geometry IS NULL)',
+            ['id' => $id]
+        );
     }
 
     private function cleanup(string $dir): void