feat(backend): persist plan scores on MealPlanItem

- Migration 0012 adds score (float) and components (jsonb) to meal_plan_item
- generate.py: populates score and components at create time
- schemas/MealPlanItemResponse: include score + components fields
- GET /api/meal-plans/{id}: returns persisted values instead of zeros

backend/app/api/meal_plans.py

@@ -125,8 +125,7 @@ def get_plan(plan_id: UUID, db: Session = Depends(get_db)) -> GenerationResponse
         .order_by(MealPlanItem.day_of_week)
         .all()
     )
-    # Read-after-create: scores not stored on MealPlanItem, so we return zeros
-    # for score/components. The original generate response is authoritative.
+    # Read-after-create: scores now stored on MealPlanItem
     return GenerationResponse(
         meal_plan_id=plan.id,
         week_start_date=plan.week_start_date,
@@ -135,8 +134,8 @@ def get_plan(plan_id: UUID, db: Session = Depends(get_db)) -> GenerationResponse
                 recipe_id=it.recipe_id,
                 day_of_week=it.day_of_week,
                 estimated_cost=it.estimated_cost or 0,
-                score=0.0,
-                components={},
+                score=it.score or 0.0,
+                components={k: float(v) for k, v in (it.components.items() if it.components else [])},
             )
             for it in items
         ],