分配計画を運搬計画に再設計: 軽トラ1回分を基本単位とする運搬回モデルを導入

実運用のワークフロー（複数施肥計画混在・軽トラ複数回・肥料指定）に合わせ、
旧 DistributionPlan/Group/GroupField を DeliveryPlan/Group/GroupField/Trip/TripItem に置き換え。
施肥計画への直接FK廃止→年度ベースで全施肥計画を横断。
回ごとの日付記録、圃場の回間移動、対象肥料フィルタ、回ごとPDF出力に対応。

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

backend/apps/fertilizer/models.py

@@ -80,51 +80,48 @@ class FertilizationEntry(models.Model):
         return f"{self.plan} / {self.field} / {self.fertilizer}: {self.bags}袋"
 
 
-class DistributionPlan(models.Model):
-    """分配計画：施肥計画の圃場をカスタムグループに割り当て、配置場所単位で集計する"""
-    fertilization_plan = models.ForeignKey(
-        FertilizationPlan, on_delete=models.CASCADE,
-        related_name='distribution_plans', verbose_name='施肥計画'
-    )
+class DeliveryPlan(models.Model):
+    """運搬計画：施肥計画の肥料を軽トラで運ぶ単位で計画・記録する"""
+    year = models.IntegerField(verbose_name='年度')
     name = models.CharField(max_length=200, verbose_name='計画名')
     created_at = models.DateTimeField(auto_now_add=True)
     updated_at = models.DateTimeField(auto_now=True)
 
     class Meta:
-        verbose_name = '分配計画'
-        verbose_name_plural = '分配計画'
-        ordering = ['-fertilization_plan__year', 'name']
+        verbose_name = '運搬計画'
+        verbose_name_plural = '運搬計画'
+        ordering = ['-year', 'name']
 
     def __str__(self):
-        return f"{self.fertilization_plan.year} {self.name}"
+        return f"{self.year} {self.name}"
 
 
-class DistributionGroup(models.Model):
-    """分配グループ：ある場所にまとめて置く圃場のグループ"""
-    distribution_plan = models.ForeignKey(
-        DistributionPlan, on_delete=models.CASCADE,
-        related_name='groups', verbose_name='分配計画'
+class DeliveryGroup(models.Model):
+    """配送先グループ：まとめて運ぶ圃場のグループ"""
+    delivery_plan = models.ForeignKey(
+        DeliveryPlan, on_delete=models.CASCADE,
+        related_name='groups', verbose_name='運搬計画'
     )
     name = models.CharField(max_length=100, verbose_name='グループ名')
     order = models.PositiveIntegerField(default=0, verbose_name='表示順')
 
     class Meta:
-        verbose_name = '分配グループ'
-        verbose_name_plural = '分配グループ'
-        unique_together = [['distribution_plan', 'name']]
+        verbose_name = '配送先グループ'
+        verbose_name_plural = '配送先グループ'
+        unique_together = [['delivery_plan', 'name']]
         ordering = ['order', 'id']
 
     def __str__(self):
-        return f"{self.distribution_plan} / {self.name}"
+        return f"{self.delivery_plan} / {self.name}"
 
 
-class DistributionGroupField(models.Model):
-    """圃場のグループへの割り当て（1圃場=1グループ/1分配計画）"""
-    distribution_plan = models.ForeignKey(
-        DistributionPlan, on_delete=models.CASCADE, verbose_name='分配計画'
+class DeliveryGroupField(models.Model):
+    """圃場のグループへの割り当て（1圃場=1グループ/1運搬計画）"""
+    delivery_plan = models.ForeignKey(
+        DeliveryPlan, on_delete=models.CASCADE, verbose_name='運搬計画'
     )
     group = models.ForeignKey(
-        DistributionGroup, on_delete=models.CASCADE,
+        DeliveryGroup, on_delete=models.CASCADE,
         related_name='field_assignments', verbose_name='グループ'
     )
     field = models.ForeignKey(
@@ -134,8 +131,51 @@ class DistributionGroupField(models.Model):
     class Meta:
         verbose_name = 'グループ圃場割り当て'
         verbose_name_plural = 'グループ圃場割り当て'
-        unique_together = [['distribution_plan', 'field']]
+        unique_together = [['delivery_plan', 'field']]
         ordering = ['field__display_order', 'field__id']
 
     def __str__(self):
         return f"{self.group.name} / {self.field.name}"
+
+
+class DeliveryTrip(models.Model):
+    """運搬回：軽トラ1回分の積載"""
+    delivery_plan = models.ForeignKey(
+        DeliveryPlan, on_delete=models.CASCADE,
+        related_name='trips', verbose_name='運搬計画'
+    )
+    order = models.PositiveIntegerField(default=0, verbose_name='何回目')
+    name = models.CharField(max_length=100, blank=True, verbose_name='名前')
+    date = models.DateField(null=True, blank=True, verbose_name='運搬日')
+
+    class Meta:
+        verbose_name = '運搬回'
+        verbose_name_plural = '運搬回'
+        ordering = ['order', 'id']
+
+    def __str__(self):
+        return f"{self.delivery_plan} / {self.order + 1}回目"
+
+
+class DeliveryTripItem(models.Model):
+    """運搬明細：圃場×肥料単位の袋数"""
+    trip = models.ForeignKey(
+        DeliveryTrip, on_delete=models.CASCADE,
+        related_name='items', verbose_name='運搬回'
+    )
+    field = models.ForeignKey(
+        'fields.Field', on_delete=models.PROTECT, verbose_name='圃場'
+    )
+    fertilizer = models.ForeignKey(
+        Fertilizer, on_delete=models.PROTECT, verbose_name='肥料'
+    )
+    bags = models.DecimalField(max_digits=10, decimal_places=4, verbose_name='袋数')
+
+    class Meta:
+        verbose_name = '運搬明細'
+        verbose_name_plural = '運搬明細'
+        unique_together = [['trip', 'field', 'fertilizer']]
+        ordering = ['field__display_order', 'field__id', 'fertilizer__name']
+
+    def __str__(self):
+        return f"{self.trip} / {self.field.name} / {self.fertilizer.name}: {self.bags}袋"