feat(backend): tunable planner weights via family profile config

- Add planner_config JSONB to family_profile model + migration
- Add PlannerConfig.merge(overrides) + to_dict() for family-level override merging
- generate_meal_plan merges family.planner_config into DEFAULT before filtering/scoring/selection
- New endpoints on /api/profile:
  - GET /planner-config — returns merged effective config
  - PUT /planner-config — partial override validation + merge
  - DELETE /planner-config — reset to system defaults
- Schemas: PlannerConfigOverride, PlannerConfigResponse, PlannerConfigUpdateRequest
  with weight-sum validation (0.999–1.001)
- Export RecipeBase/Create/Read/Update from schemas/__init__ to resolve forward refs

backend/app/services/planner/generate.py

@@ -107,6 +107,15 @@ def generate_meal_plan(
     if family is None:
         raise ValueError(f"family_profile {family_id} not found")
 
+    # Merge family-level planner overrides if present
+    effective_config = config
+    if family.planner_config:
+        from app.services.planner.config import PlannerConfig
+        try:
+            effective_config = config.merge(family.planner_config)
+        except (ValueError, TypeError) as exc:
+            logger.warning("Invalid planner_config for family %s: %s", family_id, exc)
+
     recipes = db.query(Recipe).all()
     exclude_set = exclude_recipe_ids or set()
     recipe_dicts = [
@@ -160,7 +169,7 @@ def generate_meal_plan(
         blocked_recipe_ids=blocked_recipes,
         last_cooked_at=last_cooked,
         family_calorie_target=family.calorie_target,
-        config=config,
+        config=effective_config,
         today=today,
     )
 
@@ -169,10 +178,10 @@ def generate_meal_plan(
         recipes=feasible_recipes,
         recipe_costs=recipe_costs,
         last_cooked_at=last_cooked,
-        config=config,
+        config=effective_config,
         today=today,
     )
-    chosen, set_score = select_set(scored, config)
+    chosen, set_score = select_set(scored, effective_config)
 
     plan = MealPlan(
         family_profile_id=family_id,