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/Program.cs

@@ -84,7 +84,7 @@ var app = builder.Build();
 if (app.Environment.IsDevelopment())
 {
     app.MapOpenApi();
-    
+
     using var scope = app.Services.CreateScope();
     var seedService = scope.ServiceProvider.GetRequiredService<SeedDataService>();
     await seedService.SeedAsync();
@@ -113,7 +113,7 @@ var summaries = new[]
 
 app.MapGet("/weatherforecast", () =>
 {
-    var forecast =  Enumerable.Range(1, 5).Select(index =>
+    var forecast = Enumerable.Range(1, 5).Select(index =>
         new WeatherForecast
         (
             DateOnly.FromDateTime(DateTime.Now.AddDays(index)),