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.Tests.Integration/Middleware/TenantValidationTests.cs

@@ -34,7 +34,7 @@ public class TenantValidationTests : IClassFixture<CustomWebApplicationFactory>
             { "club-1", "admin" }
         };
         var token = CreateTestJwt(clubs);
-        
+
         _client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);
         _client.DefaultRequestHeaders.Add("X-Tenant-Id", "club-1");
 
@@ -54,7 +54,7 @@ public class TenantValidationTests : IClassFixture<CustomWebApplicationFactory>
             { "club-1", "admin" }
         };
         var token = CreateTestJwt(clubs);
-        
+
         _client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);
         _client.DefaultRequestHeaders.Add("X-Tenant-Id", "club-2"); // User not member of club-2
 
@@ -74,7 +74,7 @@ public class TenantValidationTests : IClassFixture<CustomWebApplicationFactory>
             { "club-1", "admin" }
         };
         var token = CreateTestJwt(clubs);
-        
+
         _client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);
         // No X-Tenant-Id header
 
@@ -133,7 +133,7 @@ public class CustomWebApplicationFactory : WebApplicationFactory<Program>
         {
             services.AddAuthentication("TestScheme")
                 .AddScheme<AuthenticationSchemeOptions, TestAuthHandler>("TestScheme", options => { });
-            
+
             services.AddAuthorization();
         });
 
@@ -157,19 +157,19 @@ public class TestAuthHandler : AuthenticationHandler<AuthenticationSchemeOptions
     protected override Task<AuthenticateResult> HandleAuthenticateAsync()
     {
         var authHeader = Request.Headers.Authorization.ToString();
-        
+
         if (string.IsNullOrEmpty(authHeader) || !authHeader.StartsWith("Bearer "))
         {
             return Task.FromResult(AuthenticateResult.NoResult());
         }
 
         var token = authHeader.Substring("Bearer ".Length).Trim();
-        
+
         try
         {
             var handler = new JwtSecurityTokenHandler();
             var key = new SymmetricSecurityKey(Encoding.UTF8.GetBytes("test-secret-key-for-jwt-signing-must-be-at-least-32-chars"));
-            
+
             var validationParameters = new TokenValidationParameters
             {
                 ValidateIssuer = true,
@@ -183,7 +183,7 @@ public class TestAuthHandler : AuthenticationHandler<AuthenticationSchemeOptions
 
             var principal = handler.ValidateToken(token, validationParameters, out _);
             var ticket = new AuthenticationTicket(principal, "TestScheme");
-            
+
             return Task.FromResult(AuthenticateResult.Success(ticket));
         }
         catch (Exception ex)