feat(planner): replace simulatedScore with scoreDelta + hasConflict in SuggestionItem

SuggestionItem now exposes scoreDelta (simulatedScore − currentScore) and
hasConflict (scoreDelta ≤ 0) so the frontend can render badges without
needing to pass currentVarietyScore as a separate prop.

PlanningService.getSuggestions() computes currentScore once per request
and derives scoreDelta + hasConflict per candidate. Sorting is unchanged
(scoreDelta desc = simulatedScore desc since currentScore is constant).

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

backend/src/main/java/com/recipeapp/planning/PlanningService.java

@@ -135,6 +135,12 @@ public class PlanningService {
                 .map(cl -> cl.getRecipe().getId())
                 .collect(Collectors.toSet());
 
+        List<SimulatedSlot> currentSlots = plan.getSlots().stream()
+                .map(s -> new SimulatedSlot(s.getRecipe(), s.getSlotDate()))
+                .toList();
+        double currentScore = currentSlots.isEmpty() ? 10.0
+                : scoreFromSimulatedSlots(currentSlots, config, recentlyCookedIds);
+
         List<Recipe> allRecipes = recipeRepository.findByHouseholdIdAndDeletedAtIsNull(householdId);
 
         Set<String> lowerTagFilters = tagFilters.stream()
@@ -145,11 +151,13 @@ public class PlanningService {
                 .filter(r -> !usedRecipeIds.contains(r.getId()))
                 .filter(r -> matchesAllTags(r, lowerTagFilters))
                 .map(candidate -> {
-                    double score = simulateVarietyScore(
+                    double simulatedScore = simulateVarietyScore(
                             plan, candidate, slotDate, config, recentlyCookedIds);
-                    return new SuggestionResponse.SuggestionItem(toSlotRecipe(candidate), score);
+                    double scoreDelta = simulatedScore - currentScore;
+                    boolean hasConflict = scoreDelta <= 0;
+                    return new SuggestionResponse.SuggestionItem(toSlotRecipe(candidate), scoreDelta, hasConflict);
                 })
-                .sorted((a, b) -> Double.compare(b.simulatedScore(), a.simulatedScore()))
+                .sorted((a, b) -> Double.compare(b.scoreDelta(), a.scoreDelta()))
                 .limit(limit)
                 .toList();
 

backend/src/main/java/com/recipeapp/planning/dto/SuggestionResponse.java

@@ -6,6 +6,7 @@ public record SuggestionResponse(List<SuggestionItem> suggestions) {
 
     public record SuggestionItem(
             SlotResponse.SlotRecipe recipe,
-            double simulatedScore
+            double scoreDelta,
+            boolean hasConflict
     ) {}
 }