Rewrite variety score and suggestions with configurable scoring

- Add VarietyScoreConfig entity, repository, and V020 migration for
  per-household scoring weights and configurable tag types
- Rewrite getVarietyScore: tag-type repeats on consecutive days,
  non-staple ingredient overlaps, cooking log history, plan duplicates
- Rewrite getSuggestions: simulate variety score for each candidate,
  add tag filter (AND, case-insensitive) and configurable topN param
- Update SuggestionResponse to return simulatedScore instead of
  fitReasons/warnings, update VarietyScoreResponse to new shape
- Seed default VarietyScoreConfig on household creation
- Extend test suite across all domains (+270 tests, all passing)

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

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

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