feat(board): edit task deadlines

TaskTracker.Api/Pages/Board.cshtml.cs

@@ -151,7 +151,7 @@ public class BoardModel : PageModel
         return await ReturnBoardContentAsync();
     }
 
-    public async Task<IActionResult> OnPostCreateTaskAsync(string title, string? category)
+    public async Task<IActionResult> OnPostCreateTaskAsync(string title, string? category, DateTime? dueAt)
     {
         if (string.IsNullOrWhiteSpace(title))
             return BadRequest("Title is required.");
@@ -161,6 +161,7 @@ public class BoardModel : PageModel
             Title = title.Trim(),
             Category = category,
             Status = WorkTaskStatus.Pending,
+            DueAt = TaskDeadline.FromLocalInput(dueAt, TimeZoneInfo.Local),
         };
         await _taskRepo.CreateAsync(task);
 
@@ -176,7 +177,7 @@ public class BoardModel : PageModel
     }
 
     // Update task fields (inline edit)
-    public async Task<IActionResult> OnPutUpdateTaskAsync(int id, string? title, string? description, string? category, int? estimatedMinutes)
+    public async Task<IActionResult> OnPutUpdateTaskAsync(int id, string? title, string? description, string? category, int? estimatedMinutes, DateTime? dueAt, bool clearDueAt)
     {
         var task = await _taskRepo.GetByIdAsync(id);
         if (task is null) return NotFound();
@@ -185,6 +186,8 @@ public class BoardModel : PageModel
         if (description is not null) task.Description = description;
         if (category is not null) task.Category = category;
         if (estimatedMinutes.HasValue) task.EstimatedMinutes = estimatedMinutes;
+        if (clearDueAt) task.DueAt = null;
+        else if (dueAt.HasValue) task.DueAt = TaskDeadline.FromLocalInput(dueAt, TimeZoneInfo.Local);
 
         await _taskRepo.UpdateAsync(task);
         return Partial("Partials/_TaskDetail", task);