feat: prefer fbo stocks over fbs, small refactor of existing models

database/sipro/models/associations.py

@@ -23,3 +23,10 @@ warehouse_company_warehouses = Table(
     Column('company_warehouse_id', ForeignKey('company_warehouses.id')),
 
 )
+
+marketplace_fbo_warehouses = Table(
+    "marketplace_fbo_warehouses",
+    BaseSiproModel.metadata,
+    Column("marketplace_id", ForeignKey("marketplaces.id")),
+    Column("fbo_warehouse_id", ForeignKey("fbo_marketplace_warehouses.id")),
+)