Polygon cast returns bare geometry instead of SpatialExpression — spatial writes fail with MySQL error 1416

Start with Fleetbase\FleetOps\Casts\Polygon::set() and compare its typed-geometry branches with Casts\MultiPolygon. Update the related return behavior, then change server/tests/Unit/Casts/SpatialCastBranchesTest.php to expect SpatialExpression for Polygon. Run that test and the TestingSeeder; done means the seeders complete and zones write correctly.

Bug

Fleetbase\FleetOps\Casts\Polygon::set() returns the bare Polygon object for typed geometries, while Casts\Point and Casts\MultiPolygon wrap theirs in SpatialExpression.

Laravel re-runs class casts during getAttributes() (mergeAttributesFromClassCasts), so the second set() call overwrites the SpatialExpression that SpatialTrait::performInsert() prepared. The raw Polygon object ends up bound to the query, PDO stringifies it to (lng lat, ...), and MySQL rejects the write:

SQLSTATE[22003]: Numeric value out of range: 1416 Cannot get geometry
object from data you send to the GEOMETRY field

Reproduction

On a fresh Docker install (fleetbase/fleetbase-api:latest, bundled mysql:8.0-oracle), create a company then run:

php artisan db:seed --class="Fleetbase\FleetOps\Seeders\Testing\TestingSeeder"

NetworkSeeder fails inserting zones.border. The same path breaks Zone creation through the API — any border write is affected.

Fix

Mirror Casts\MultiPolygon — wrap typed geometries in SpatialExpression:

         // Checked before the broader GeometryInterface guard below, which a
-        // SpatialPolygon also satisfies — otherwise this arm never fires. Both
-        // arms behave identically, so ordering does not change what is stored.
+        // SpatialPolygon also satisfies — otherwise this arm never fires.
+        // It must wrap in a SpatialExpression exactly as that guard does:
+        // returning the bare geometry here would change what is bound on writes
+        // that skip SpatialTrait::performInsert().
         if ($value instanceof SpatialPolygon) {
             $model->geometries[$key] = $value;
 
-            return $value;
+            return new SpatialExpression($value);
         }
 
         if ($value instanceof GeometryInterface) {
             $model->geometries[$key] = $value;
 
-            return $value;
+            return new SpatialExpression($value);
         }

The GeoJSON and SpatialExpression branches are fine as-is — non-object inputs never enter the cast cache, so they skip the re-serialisation path.

server/tests/Unit/Casts/SpatialCastBranchesTest.php currently asserts the old behavior (expect($polygonCast)->toBe($polygon)); it should expect SpatialExpression like the MultiPolygon assertion above it.

Verified: with the patch, the testing seeders complete and zones write correctly.