Implement Recipe, Planning, Shopping, Pantry, and Admin domains

Outside-in TDD for all 5 remaining domains (128 tests total):
- Recipe: CRUD, ingredients autocomplete/patch, tags, categories (27 tests)
- Planning: week plans, slots, confirm, suggestions, variety score, cooking logs (24 tests)
- Shopping: generate from plan, publish, check/add/remove items (15 tests)
- Pantry: CRUD with expiry sorting (11 tests)
- Admin: user management, password reset, audit logging (13 tests)

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

backend/src/main/java/com/recipeapp/recipe/HouseholdResolver.java

@@ -0,0 +1,31 @@
+package com.recipeapp.recipe;
+
+import com.recipeapp.common.ResourceNotFoundException;
+import com.recipeapp.household.HouseholdMemberRepository;
+import com.recipeapp.household.entity.HouseholdMember;
+import org.springframework.stereotype.Component;
+
+import java.util.UUID;
+
+@Component
+public class HouseholdResolver {
+
+    private final HouseholdMemberRepository householdMemberRepository;
+
+    public HouseholdResolver(HouseholdMemberRepository householdMemberRepository) {
+        this.householdMemberRepository = householdMemberRepository;
+    }
+
+    public UUID resolve(String userEmail) {
+        return findMembership(userEmail).getHousehold().getId();
+    }
+
+    public UUID resolveUserId(String userEmail) {
+        return findMembership(userEmail).getUser().getId();
+    }
+
+    private HouseholdMember findMembership(String userEmail) {
+        return householdMemberRepository.findByUserEmailIgnoreCase(userEmail)
+                .orElseThrow(() -> new ResourceNotFoundException("User is not in a household"));
+    }
+}