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.Infrastructure/Data/Interceptors/SaveChangesTenantInterceptor.cs

@@ -39,10 +39,11 @@ public class SaveChangesTenantInterceptor : SaveChangesInterceptor
 
     private void SetTenantIdForNewEntities(DbContext? context)
     {
-        if (context == null) return;
+        if (context == null)
+            return;
 
         var tenantId = _tenantAccessor.MultiTenantContext?.TenantInfo?.Identifier;
-        
+
         if (string.IsNullOrWhiteSpace(tenantId))
         {
             _logger.LogWarning("No tenant context available for SaveChanges");
@@ -61,7 +62,7 @@ public class SaveChangesTenantInterceptor : SaveChangesInterceptor
                 if (string.IsNullOrWhiteSpace(tenantEntity.TenantId))
                 {
                     tenantEntity.TenantId = tenantId;
-                    _logger.LogDebug("Set TenantId for entity {EntityType}: {TenantId}", 
+                    _logger.LogDebug("Set TenantId for entity {EntityType}: {TenantId}",
                         entry.Entity.GetType().Name, tenantId);
                 }
             }