feat: migrate ClientController to FastEndpoints Endpoints (Phase 4)

IMPLEMENTATION:
- Create 5 FastEndpoints Endpoint classes for Client API:
  - GetPagedEndpoint: GET /api/client (auth, paginated + filters)
  - GetByIdEndpoint: GET /api/client/{id} (auth)
  - CreateEndpoint: POST /api/client (auth)
  - UpdateEndpoint: PUT /api/client/{id} (auth)
  - DeleteEndpoint: DELETE /api/client/{id} (auth)

- Create ClientDtos.cs with query/response types
- Backup ClientController.cs

VERIFICATION:
✅ dotnet build: 0 errors, 0 warnings
✅ dotnet test: 26/26 passed

PROGRESS:
✅ Phase 1: Auth (4 endpoints) - DEPLOYED
✅ Phase 2: Blog (10 endpoints) - DEPLOYED
✅ Phase 3: Inquiry (7 endpoints) - DEPLOYED
✅ Phase 4: Client (5 endpoints) - READY

Remaining: 12 Controllers (TaxProfile, TaxFilingSchedule, Contract, etc.)

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

src/TaxBaik.Web/Endpoints/Client/ClientDtos.cs

@@ -0,0 +1,22 @@
+namespace TaxBaik.Web.Endpoints.Client;
+
+public class ClientQuery
+{
+    public int Page { get; set; } = 1;
+    public int PageSize { get; set; } = 20;
+    public string? Status { get; set; }
+    public string? Search { get; set; }
+}
+
+public class ClientPagedResponse
+{
+    public List<object> Data { get; set; } = [];
+    public int Total { get; set; }
+    public int Page { get; set; }
+    public int PageSize { get; set; }
+}
+
+public class MessageResponse
+{
+    public string Message { get; set; } = string.Empty;
+}

src/TaxBaik.Web/Endpoints/Client/CreateEndpoint.cs

@@ -0,0 +1,35 @@
+using FastEndpoints;
+using TaxBaik.Application.DTOs;
+using TaxBaik.Application.Services;
+
+namespace TaxBaik.Web.Endpoints.Client;
+
+public class CreateEndpoint : Endpoint<CreateClientDto, object>
+{
+    private readonly ClientService _clientService;
+
+    public CreateEndpoint(ClientService clientService)
+    {
+        _clientService = clientService;
+    }
+
+    public override void Configure()
+    {
+        Post("/api/client");
+        Policies("Bearer");
+    }
+
+    public override async Task HandleAsync(CreateClientDto request, CancellationToken ct)
+    {
+        try
+        {
+            var clientId = await _clientService.CreateAsync(request);
+            var client = await _clientService.GetByIdAsync(clientId) ?? request;
+            await SendAsync(client, 201, cancellation: ct);
+        }
+        catch (ValidationException ex)
+        {
+            ThrowError(ex.Message);
+        }
+    }
+}

src/TaxBaik.Web/Endpoints/Client/DeleteEndpoint.cs

@@ -0,0 +1,27 @@
+using FastEndpoints;
+using TaxBaik.Application.Services;
+
+namespace TaxBaik.Web.Endpoints.Client;
+
+public class DeleteEndpoint : Endpoint<EmptyRequest, EmptyResponse>
+{
+    private readonly ClientService _clientService;
+
+    public DeleteEndpoint(ClientService clientService)
+    {
+        _clientService = clientService;
+    }
+
+    public override void Configure()
+    {
+        Delete("/api/client/{id}");
+        Policies("Bearer");
+    }
+
+    public override async Task HandleAsync(EmptyRequest _, CancellationToken ct)
+    {
+        var id = Route<int>("id");
+        await _clientService.DeleteAsync(id);
+        await SendAsync(new EmptyResponse(), 204, cancellation: ct);
+    }
+}

src/TaxBaik.Web/Endpoints/Client/GetByIdEndpoint.cs

@@ -0,0 +1,32 @@
+using FastEndpoints;
+using TaxBaik.Application.Services;
+
+namespace TaxBaik.Web.Endpoints.Client;
+
+public class GetByIdEndpoint : Endpoint<EmptyRequest, object>
+{
+    private readonly ClientService _clientService;
+
+    public GetByIdEndpoint(ClientService clientService)
+    {
+        _clientService = clientService;
+    }
+
+    public override void Configure()
+    {
+        Get("/api/client/{id}");
+        Policies("Bearer");
+    }
+
+    public override async Task HandleAsync(EmptyRequest _, CancellationToken ct)
+    {
+        var id = Route<int>("id");
+        var client = await _clientService.GetByIdAsync(id);
+        if (client == null)
+        {
+            ThrowError("고객을 찾을 수 없습니다.", statusCode: 404);
+        }
+
+        await SendAsync(client, 200, cancellation: ct);
+    }
+}

src/TaxBaik.Web/Endpoints/Client/GetPagedEndpoint.cs

@@ -0,0 +1,32 @@
+using FastEndpoints;
+using TaxBaik.Application.Services;
+
+namespace TaxBaik.Web.Endpoints.Client;
+
+public class GetPagedEndpoint : Endpoint<ClientQuery, ClientPagedResponse>
+{
+    private readonly ClientService _clientService;
+
+    public GetPagedEndpoint(ClientService clientService)
+    {
+        _clientService = clientService;
+    }
+
+    public override void Configure()
+    {
+        Get("/api/client");
+        Policies("Bearer");
+    }
+
+    public override async Task HandleAsync(ClientQuery request, CancellationToken ct)
+    {
+        var (clients, total) = await _clientService.GetPagedAsync(request.Page, request.PageSize, request.Status, request.Search);
+        await SendAsync(new ClientPagedResponse
+        {
+            Data = clients.Cast<object>().ToList(),
+            Total = total,
+            Page = request.Page,
+            PageSize = request.PageSize
+        }, 200, cancellation: ct);
+    }
+}

src/TaxBaik.Web/Endpoints/Client/UpdateEndpoint.cs

@@ -0,0 +1,41 @@
+using FastEndpoints;
+using TaxBaik.Application.DTOs;
+using TaxBaik.Application.Services;
+
+namespace TaxBaik.Web.Endpoints.Client;
+
+public class UpdateEndpoint : Endpoint<CreateClientDto, object>
+{
+    private readonly ClientService _clientService;
+
+    public UpdateEndpoint(ClientService clientService)
+    {
+        _clientService = clientService;
+    }
+
+    public override void Configure()
+    {
+        Put("/api/client/{id}");
+        Policies("Bearer");
+    }
+
+    public override async Task HandleAsync(CreateClientDto request, CancellationToken ct)
+    {
+        var id = Route<int>("id");
+        try
+        {
+            await _clientService.UpdateAsync(id, request);
+            var client = await _clientService.GetByIdAsync(id);
+            if (client == null)
+            {
+                ThrowError("고객을 찾을 수 없습니다.", statusCode: 404);
+            }
+
+            await SendAsync(client, 200, cancellation: ct);
+        }
+        catch (ValidationException ex)
+        {
+            ThrowError(ex.Message);
+        }
+    }
+}