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/admin.py

@@ -1,5 +1,8 @@
 from django.contrib import admin
-from .models import Fertilizer, FertilizationPlan, FertilizationEntry, DistributionPlan, DistributionGroup, DistributionGroupField
+from .models import (
+    Fertilizer, FertilizationPlan, FertilizationEntry,
+    DeliveryPlan, DeliveryGroup, DeliveryGroupField, DeliveryTrip, DeliveryTripItem,
+)
 
 
 @admin.register(Fertilizer)
@@ -19,25 +22,41 @@ class FertilizationPlanAdmin(admin.ModelAdmin):
     inlines = [FertilizationEntryInline]
 
 
-class DistributionGroupFieldInline(admin.TabularInline):
-    model = DistributionGroupField
+class DeliveryGroupFieldInline(admin.TabularInline):
+    model = DeliveryGroupField
     extra = 0
-    readonly_fields = ['distribution_plan']
+    readonly_fields = ['delivery_plan']
 
 
-class DistributionGroupInline(admin.TabularInline):
-    model = DistributionGroup
+class DeliveryGroupInline(admin.TabularInline):
+    model = DeliveryGroup
     extra = 0
 
 
-@admin.register(DistributionPlan)
-class DistributionPlanAdmin(admin.ModelAdmin):
-    list_display = ['name', 'fertilization_plan', 'created_at']
-    list_filter = ['fertilization_plan__year']
-    inlines = [DistributionGroupInline]
+class DeliveryTripItemInline(admin.TabularInline):
+    model = DeliveryTripItem
+    extra = 0
 
 
-@admin.register(DistributionGroup)
-class DistributionGroupAdmin(admin.ModelAdmin):
-    list_display = ['name', 'distribution_plan', 'order']
-    inlines = [DistributionGroupFieldInline]
+class DeliveryTripInline(admin.TabularInline):
+    model = DeliveryTrip
+    extra = 0
+
+
+@admin.register(DeliveryPlan)
+class DeliveryPlanAdmin(admin.ModelAdmin):
+    list_display = ['name', 'year', 'created_at']
+    list_filter = ['year']
+    inlines = [DeliveryGroupInline, DeliveryTripInline]
+
+
+@admin.register(DeliveryGroup)
+class DeliveryGroupAdmin(admin.ModelAdmin):
+    list_display = ['name', 'delivery_plan', 'order']
+    inlines = [DeliveryGroupFieldInline]
+
+
+@admin.register(DeliveryTrip)
+class DeliveryTripAdmin(admin.ModelAdmin):
+    list_display = ['delivery_plan', 'order', 'name', 'date']
+    inlines = [DeliveryTripItemInline]