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/admin/AdminUserQueryRepository.java

@@ -0,0 +1,19 @@
+package com.recipeapp.admin;
+
+import com.recipeapp.auth.entity.UserAccount;
+import org.springframework.data.domain.Pageable;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.repository.query.Param;
+
+import java.util.List;
+import java.util.UUID;
+
+public interface AdminUserQueryRepository extends JpaRepository<UserAccount, UUID> {
+
+    @Query("SELECT u FROM UserAccount u WHERE (:search IS NULL OR LOWER(u.email) LIKE LOWER(CONCAT('%', :search, '%')) OR LOWER(u.displayName) LIKE LOWER(CONCAT('%', :search, '%'))) AND (:isActive IS NULL OR u.isActive = :isActive)")
+    List<UserAccount> findUsersFiltered(@Param("search") String search, @Param("isActive") Boolean isActive, Pageable pageable);
+
+    @Query("SELECT COUNT(u) FROM UserAccount u WHERE (:search IS NULL OR LOWER(u.email) LIKE LOWER(CONCAT('%', :search, '%')) OR LOWER(u.displayName) LIKE LOWER(CONCAT('%', :search, '%'))) AND (:isActive IS NULL OR u.isActive = :isActive)")
+    long countUsersFiltered(@Param("search") String search, @Param("isActive") Boolean isActive);
+}