feat: migrate TaxFilingScheduleController to FastEndpoints (Phase 6)

IMPLEMENTATION:
- Create 7 FastEndpoints Endpoints:
  - CreateEndpoint, GetByIdEndpoint, GetAllEndpoint
  - GetByClientIdEndpoint, GetUpcomingEndpoint
  - MarkCompletedEndpoint, GetPendingCountEndpoint

Total: 38 endpoints migrated (out of 73)
Remaining: 12 Controllers (35 endpoints)

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

src/TaxBaik.Web/Endpoints/TaxFilingSchedule/AllEndpoints.cs

@@ -0,0 +1,149 @@
+using FastEndpoints;
+using TaxBaik.Application.Services;
+
+namespace TaxBaik.Web.Endpoints.TaxFilingSchedule;
+
+public class CreateRequest
+{
+    public int ClientId { get; set; }
+    public string? FilingType { get; set; }
+    public DateTime DueDate { get; set; }
+    public int FilingYear { get; set; }
+    public int? AssignedToId { get; set; }
+}
+
+public class IdResponse { public int Id { get; set; } }
+public class MessageResponse { public string Message { get; set; } = string.Empty; }
+public class ListResponse { public List<object> Data { get; set; } = []; }
+public class CountResponse { public int Count { get; set; } }
+public class DaysQuery { public int DaysAhead { get; set; } = 30; }
+
+public class CreateEndpoint : Endpoint<CreateRequest, IdResponse>
+{
+    private readonly TaxFilingScheduleService _svc;
+    public CreateEndpoint(TaxFilingScheduleService svc) => _svc = svc;
+
+    public override void Configure()
+    {
+        Post("/api/taxfilingschedule");
+        Policies("Bearer");
+    }
+
+    public override async Task HandleAsync(CreateRequest req, CancellationToken ct)
+    {
+        var id = await _svc.CreateAsync(req.ClientId, req.FilingType, req.DueDate, req.FilingYear, req.AssignedToId);
+        await SendAsync(new IdResponse { Id = id }, 201, cancellation: ct);
+    }
+}
+
+public class GetByIdEndpoint : Endpoint<EmptyRequest, object>
+{
+    private readonly TaxFilingScheduleService _svc;
+    public GetByIdEndpoint(TaxFilingScheduleService svc) => _svc = svc;
+
+    public override void Configure()
+    {
+        Get("/api/taxfilingschedule/{id}");
+        Policies("Bearer");
+    }
+
+    public override async Task HandleAsync(EmptyRequest _, CancellationToken ct)
+    {
+        var id = Route<int>("id");
+        var schedule = await _svc.GetByIdAsync(id);
+        if (schedule == null) ThrowError("일정을 찾을 수 없습니다.", statusCode: 404);
+        await SendAsync(schedule, 200, cancellation: ct);
+    }
+}
+
+public class GetAllEndpoint : Endpoint<EmptyRequest, ListResponse>
+{
+    private readonly TaxFilingScheduleService _svc;
+    public GetAllEndpoint(TaxFilingScheduleService svc) => _svc = svc;
+
+    public override void Configure()
+    {
+        Get("/api/taxfilingschedule");
+        Policies("Bearer");
+    }
+
+    public override async Task HandleAsync(EmptyRequest _, CancellationToken ct)
+    {
+        var schedules = await _svc.GetAllAsync();
+        await SendAsync(new ListResponse { Data = schedules.Cast<object>().ToList() }, 200, cancellation: ct);
+    }
+}
+
+public class GetByClientIdEndpoint : Endpoint<EmptyRequest, ListResponse>
+{
+    private readonly TaxFilingScheduleService _svc;
+    public GetByClientIdEndpoint(TaxFilingScheduleService svc) => _svc = svc;
+
+    public override void Configure()
+    {
+        Get("/api/taxfilingschedule/client/{clientId}");
+        Policies("Bearer");
+    }
+
+    public override async Task HandleAsync(EmptyRequest _, CancellationToken ct)
+    {
+        var clientId = Route<int>("clientId");
+        var schedules = await _svc.GetByClientIdAsync(clientId);
+        await SendAsync(new ListResponse { Data = schedules.Cast<object>().ToList() }, 200, cancellation: ct);
+    }
+}
+
+public class GetUpcomingEndpoint : Endpoint<DaysQuery, object>
+{
+    private readonly TaxFilingScheduleService _svc;
+    public GetUpcomingEndpoint(TaxFilingScheduleService svc) => _svc = svc;
+
+    public override void Configure()
+    {
+        Get("/api/taxfilingschedule/upcoming");
+        Policies("Bearer");
+    }
+
+    public override async Task HandleAsync(DaysQuery req, CancellationToken ct)
+    {
+        var schedules = await _svc.GetUpcomingDuesAsync(req.DaysAhead);
+        await SendAsync(new { data = schedules, daysAhead = req.DaysAhead }, 200, cancellation: ct);
+    }
+}
+
+public class MarkCompletedEndpoint : Endpoint<EmptyRequest, MessageResponse>
+{
+    private readonly TaxFilingScheduleService _svc;
+    public MarkCompletedEndpoint(TaxFilingScheduleService svc) => _svc = svc;
+
+    public override void Configure()
+    {
+        Post("/api/taxfilingschedule/{id}/completed");
+        Policies("Bearer");
+    }
+
+    public override async Task HandleAsync(EmptyRequest _, CancellationToken ct)
+    {
+        var id = Route<int>("id");
+        await _svc.MarkCompletedAsync(id);
+        await SendAsync(new MessageResponse { Message = "완료 처리되었습니다." }, 200, cancellation: ct);
+    }
+}
+
+public class GetPendingCountEndpoint : Endpoint<EmptyRequest, CountResponse>
+{
+    private readonly TaxFilingScheduleService _svc;
+    public GetPendingCountEndpoint(TaxFilingScheduleService svc) => _svc = svc;
+
+    public override void Configure()
+    {
+        Get("/api/taxfilingschedule/pending/count");
+        Policies("Bearer");
+    }
+
+    public override async Task HandleAsync(EmptyRequest _, CancellationToken ct)
+    {
+        var count = await _svc.GetPendingCountAsync();
+        await SendAsync(new CountResponse { Count = count }, 200, cancellation: ct);
+    }
+}