施肥計画の計算設定を保存・復元し、未入力圃場のみ計算オプションを追加

- FertilizationPlanにcalc_settings JSONFieldを追加（migration 0004）
- 編集画面を開くと前回の計算方式・パラメータが復元される
- 「未入力圃場のみ」チェックで既存値を保持したまま新規圃場だけ計算可能

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

backend/apps/fertilizer/migrations/0004_fertilizationplan_calc_settings.py

@@ -0,0 +1,16 @@
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('fertilizer', '0003_distributionplan_distributiongroup_and_more'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='fertilizationplan',
+            name='calc_settings',
+            field=models.JSONField(blank=True, default=list, verbose_name='計算設定'),
+        ),
+    ]

backend/apps/fertilizer/models.py

@@ -34,6 +34,7 @@ class FertilizationPlan(models.Model):
         'plans.Variety', on_delete=models.PROTECT,
         related_name='fertilization_plans', verbose_name='品種'
     )
+    calc_settings = models.JSONField(default=list, blank=True, verbose_name='計算設定')
     created_at = models.DateTimeField(auto_now_add=True)
     updated_at = models.DateTimeField(auto_now=True)
 

backend/apps/fertilizer/serializers.py

@@ -31,7 +31,7 @@ class FertilizationPlanSerializer(serializers.ModelSerializer):
         model = FertilizationPlan
         fields = [
             'id', 'name', 'year', 'variety', 'variety_name', 'crop_name',
-            'entries', 'field_count', 'fertilizer_count', 'created_at', 'updated_at'
+            'calc_settings', 'entries', 'field_count', 'fertilizer_count', 'created_at', 'updated_at'
         ]
 
     def get_variety_name(self, obj):
@@ -53,7 +53,7 @@ class FertilizationPlanWriteSerializer(serializers.ModelSerializer):
 
     class Meta:
         model = FertilizationPlan
-        fields = ['id', 'name', 'year', 'variety', 'entries']
+        fields = ['id', 'name', 'year', 'variety', 'calc_settings', 'entries']
 
     def create(self, validated_data):
         entries_data = validated_data.pop('entries', [])