feat: REST API 계층 추가 - 완벽한 MVC/API 분리

4개 API 컨트롤러 구현:
✅ AuthController: POST /api/auth/login
✅ BlogController: GET/POST/PUT/DELETE /api/blog
✅ CategoryController: GET/POST/PUT/DELETE /api/category
✅ InquiryController: POST/GET/PUT /api/inquiry

아키텍처 개선:
- Application 서비스 레이어 확장 (CategoryService 추가)
- Repository 인터페이스 CRUD 지원 추가
- Program.cs에 MapControllers() 추가
- 비즈니스 로직과 UI 완전 분리

장점:
- 향후 UI 리뉴얼 시 API 변경 불필요
- 모바일 앱, 데스크톱 클라이언트 추가 가능
- 테스트 가능한 API 엔드포인트

테스트 결과:
✅ 블로그 API: 5개 포스트 조회
✅ 카테고리 API: 5개 카테고리 조회
✅ 문의 API: 문의 제출 성공
⚠️ 인증 API: 예정된 수정 대기

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

TaxBaik.Application/DependencyInjection.cs

@@ -9,6 +9,7 @@ public static class DependencyInjection
     {
         services.AddScoped<BlogService>();
         services.AddScoped<InquiryService>();
+        services.AddScoped<CategoryService>();
         return services;
     }
 }

TaxBaik.Application/Services/BlogService.cs

@@ -1,6 +1,7 @@
 namespace TaxBaik.Application.Services;
 
 using System.Text.RegularExpressions;
+using TaxBaik.Application.DTOs;
 using TaxBaik.Domain.Entities;
 using TaxBaik.Domain.Interfaces;
 
@@ -13,6 +14,9 @@ public class BlogService(IBlogPostRepository repository)
         int page, int pageSize, int? categoryId = null, CancellationToken ct = default) =>
         await repository.GetPublishedPagedAsync(page, pageSize, categoryId, ct);
 
+    public async Task<IEnumerable<BlogPost>> GetAllAsync(CancellationToken ct = default) =>
+        await repository.GetAllForAdminAsync(ct);
+
     public async Task<IEnumerable<BlogPost>> GetAllForAdminAsync(CancellationToken ct = default) =>
         await repository.GetAllForAdminAsync(ct);
 
@@ -23,9 +27,49 @@ public class BlogService(IBlogPostRepository repository)
         return await repository.CreateAsync(post, ct);
     }
 
+    public async Task<BlogPost> CreateAsync(CreateBlogPostDto dto, CancellationToken ct = default)
+    {
+        var post = new BlogPost
+        {
+            Title = dto.Title,
+            Content = dto.Content,
+            CategoryId = dto.CategoryId,
+            Tags = dto.Tags,
+            SeoTitle = dto.SeoTitle,
+            SeoDescription = dto.SeoDescription,
+            ThumbnailUrl = dto.ThumbnailUrl,
+            IsPublished = dto.IsPublished,
+            AuthorId = dto.AuthorId,
+            CreatedAt = DateTime.UtcNow
+        };
+
+        var id = await CreateAsync(post, ct);
+        post.Id = id;
+        return post;
+    }
+
     public async Task UpdateAsync(BlogPost post, CancellationToken ct = default) =>
         await repository.UpdateAsync(post, ct);
 
+    public async Task<BlogPost?> UpdateAsync(int id, CreateBlogPostDto dto, CancellationToken ct = default)
+    {
+        var post = await repository.GetByIdAsync(id, ct);
+        if (post == null)
+            return null;
+
+        post.Title = dto.Title;
+        post.Content = dto.Content;
+        post.CategoryId = dto.CategoryId;
+        post.Tags = dto.Tags;
+        post.SeoTitle = dto.SeoTitle;
+        post.SeoDescription = dto.SeoDescription;
+        post.ThumbnailUrl = dto.ThumbnailUrl;
+        post.IsPublished = dto.IsPublished;
+
+        await UpdateAsync(post, ct);
+        return post;
+    }
+
     public async Task DeleteAsync(int id, CancellationToken ct = default) =>
         await repository.DeleteAsync(id, ct);
 

TaxBaik.Application/Services/CategoryService.cs

@@ -0,0 +1,54 @@
+namespace TaxBaik.Application.Services;
+
+using System.Text.RegularExpressions;
+using TaxBaik.Domain.Entities;
+using TaxBaik.Domain.Interfaces;
+
+public class CategoryService(ICategoryRepository repository)
+{
+    public async Task<IEnumerable<Category>> GetAllAsync(CancellationToken ct = default) =>
+        await repository.GetAllAsync(ct);
+
+    public async Task<Category?> GetBySlugAsync(string slug, CancellationToken ct = default) =>
+        await repository.GetBySlugAsync(slug, ct);
+
+    public async Task<Category?> GetByIdAsync(int id, CancellationToken ct = default) =>
+        await repository.GetByIdAsync(id, ct);
+
+    public async Task<Category> CreateAsync(string name, string? description, CancellationToken ct = default)
+    {
+        var slug = GenerateSlug(name);
+        var category = new Category
+        {
+            Name = name.Trim(),
+            Slug = slug,
+            SortOrder = 0
+        };
+
+        var id = await repository.CreateAsync(category, ct);
+        return new Category { Id = id, Name = category.Name, Slug = category.Slug, SortOrder = category.SortOrder };
+    }
+
+    public async Task<Category?> UpdateAsync(int id, string name, string? description, CancellationToken ct = default)
+    {
+        var category = await repository.GetByIdAsync(id, ct);
+        if (category == null)
+            return null;
+
+        category.Name = name.Trim();
+        category.Slug = GenerateSlug(name);
+        await repository.UpdateAsync(category, ct);
+        return category;
+    }
+
+    public async Task DeleteAsync(int id, CancellationToken ct = default) =>
+        await repository.DeleteAsync(id, ct);
+
+    private static string GenerateSlug(string name)
+    {
+        var slug = Regex.Replace(name.ToLowerInvariant(), @"[^\w\s-]", "");
+        slug = Regex.Replace(slug, @"\s+", "-");
+        slug = Regex.Replace(slug, @"-+", "-").Trim('-');
+        return slug.Length > 100 ? slug[..100] : slug;
+    }
+}