style(backend): apply dotnet format whitespace normalization

- Applied dotnet format to 24 files in backend/
- Corrects spacing, indentation, and formatting consistency
- No functional changes to code logic

Ultraworked with Sisyphus <https://github.com/code-yeongyu/oh-my-opencode>
Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

backend/WorkClub.Api/Services/TaskService.cs

@@ -52,7 +52,7 @@ public class TaskService
     public async Task<TaskDetailDto?> GetTaskByIdAsync(Guid id)
     {
         var workItem = await _context.WorkItems.FindAsync(id);
-        
+
         if (workItem == null)
             return null;
 
@@ -73,7 +73,7 @@ public class TaskService
     public async Task<(TaskDetailDto? task, string? error)> CreateTaskAsync(CreateTaskRequest request, Guid createdById)
     {
         var tenantId = _tenantProvider.GetTenantId();
-        
+
         var workItem = new WorkItem
         {
             Id = Guid.NewGuid(),
@@ -111,7 +111,7 @@ public class TaskService
     public async Task<(TaskDetailDto? task, string? error, bool isConflict)> UpdateTaskAsync(Guid id, UpdateTaskRequest request)
     {
         var workItem = await _context.WorkItems.FindAsync(id);
-        
+
         if (workItem == null)
             return (null, "Task not found", false);
 
@@ -172,7 +172,7 @@ public class TaskService
     public async Task<bool> DeleteTaskAsync(Guid id)
     {
         var workItem = await _context.WorkItems.FindAsync(id);
-        
+
         if (workItem == null)
             return false;