feat: WBS-CRM-01 고객 카드 (Client Card) Phase 1 구현

DB:
- V006__CreateClients.sql: clients 테이블 (name, company_name, phone,
  email, service_type, tax_type, status, source, memo)

Domain:
- Client 엔티티
- IClientRepository (GetPagedAsync 이름/연락처/회사명 검색 + 상태 필터)

Infrastructure:
- ClientRepository: ILIKE 검색, 페이징, CRUD

Application:
- ClientService: ServiceTypes/TaxTypes/Sources 상수 정의
- CreateClientDto

Admin UI:
- ClientList.razor: 검색바 + 상태 필터 + 페이징 테이블
- ClientEdit.razor: 기본정보/세무정보/관리정보 섹션 폼
- MainLayout: 고객 관리 NavGroup 추가, 홈페이지 메뉴 그룹화

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

TaxBaik.Domain/Interfaces/IClientRepository.cs

@@ -0,0 +1,14 @@
+namespace TaxBaik.Domain.Interfaces;
+
+using TaxBaik.Domain.Entities;
+
+public interface IClientRepository
+{
+    Task<(IEnumerable<Client> Items, int Total)> GetPagedAsync(
+        int page, int pageSize, string? status = null, string? search = null,
+        CancellationToken ct = default);
+    Task<Client?> GetByIdAsync(int id, CancellationToken ct = default);
+    Task<int> CreateAsync(Client client, CancellationToken ct = default);
+    Task UpdateAsync(Client client, CancellationToken ct = default);
+    Task DeleteAsync(int id, CancellationToken ct = default);
+}