Change model to Claude Sonnet 4.5 and move C# usings to GlobalUsings.cs

Co-authored-by: Behnam-Emamian <9818491+Behnam-Emamian@users.noreply.github.com>

Author: Copilot

.github/chatmodes/backend-developer.chatmode.md

@@ -1,7 +1,7 @@
 ---
 description: "Expert in .NET backend development with Entity Framework Core and REST APIs for Oqtane"
 tools: [editFiles, search, codebase]
-model: gpt-4
+model: claude-sonnet-4.5
 ---
 
 # .NET Backend Developer
@@ -48,12 +48,25 @@ When working with controllers, services, repositories, Entity Framework, or data
 
 When asked to create backend code, provide implementations like this:
 
-### Entity Model
+### GlobalUsings.cs
+All common using statements should be placed in `GlobalUsings.cs`:
+
 ```csharp
-using System;
-using System.ComponentModel.DataAnnotations;
-using System.ComponentModel.DataAnnotations.Schema;
+global using System;
+global using System.Collections.Generic;
+global using System.ComponentModel.DataAnnotations;
+global using System.ComponentModel.DataAnnotations.Schema;
+global using System.Linq;
+global using System.Threading.Tasks;
+global using Microsoft.AspNetCore.Authorization;
+global using Microsoft.AspNetCore.Http;
+global using Microsoft.AspNetCore.Mvc;
+global using Microsoft.EntityFrameworkCore;
+global using Microsoft.Extensions.Logging;
+```
 
+### Entity Model
+```csharp
 namespace ICTAce.FileHub.Shared.Models
 {
     /// <summary>
@@ -103,11 +116,6 @@ namespace ICTAce.FileHub.Shared.Models
 
 ### Repository Interface and Implementation
 ```csharp
-using System.Collections.Generic;
-using System.Threading.Tasks;
-using ICTAce.FileHub.Shared.Models;
-using Oqtane.Repository;
-
 namespace ICTAce.FileHub.Server.Repository
 {
     /// <summary>
@@ -193,10 +201,6 @@ namespace ICTAce.FileHub.Server.Repository
 
 ### Service Layer
 ```csharp
-using System.Collections.Generic;
-using System.Threading.Tasks;
-using ICTAce.FileHub.Shared.Models;
-
 namespace ICTAce.FileHub.Server.Services
 {
     public interface IFileService
@@ -279,10 +283,6 @@ namespace ICTAce.FileHub.Server.Services
 
 ### REST API Controller
 ```csharp
-using Microsoft.AspNetCore.Authorization;
-using Microsoft.AspNetCore.Mvc;
-using Microsoft.AspNetCore.Http;
-
 namespace ICTAce.FileHub.Server.Controllers
 {
     [Authorize]

.github/chatmodes/blazor-developer.chatmode.md

@@ -1,7 +1,7 @@
 ---
 description: "Expert in building Blazor components with Syncfusion in Oqtane CMS"
 tools: [editFiles, search, codebase]
-model: gpt-4
+model: claude-sonnet-4.5
 ---
 
 # Blazor Developer

.github/chatmodes/devops-engineer.chatmode.md

@@ -1,7 +1,7 @@
 ---
 description: "Expert in CI/CD pipelines, GitHub Actions, Docker, and deployment automation"
 tools: [editFiles, search, codebase]
-model: gpt-4
+model: claude-sonnet-4.5
 ---
 
 # DevOps Engineer

.github/chatmodes/html-designer.chatmode.md

@@ -1,7 +1,7 @@
 ---
 description: "Expert in HTML5, CSS3, and modern responsive design for Oqtane themes"
 tools: [editFiles, search, codebase]
-model: gpt-4
+model: claude-sonnet-4.5
 ---
 
 # HTML Designer

.github/chatmodes/tester.chatmode.md

@@ -1,7 +1,7 @@
 ---
 description: "Expert in testing with BUnit, TUnit, and Reqnroll for comprehensive test coverage"
 tools: [editFiles, search, codebase]
-model: gpt-4
+model: claude-sonnet-4.5
 ---
 
 # Tester
@@ -45,15 +45,25 @@ When working with test files or testing-related tasks, you should:
 
 ## Example Patterns
 
-### TUnit Tests (Unit Testing)
+### GlobalUsings.cs for Tests
+All common using statements should be placed in `GlobalUsings.cs`:
+
 ```csharp
-using TUnit.Core;
-using Moq;
-using FluentAssertions;
-using ICTAce.FileHub.Server.Services;
-using ICTAce.FileHub.Server.Repository;
-using ICTAce.FileHub.Shared.Models;
+global using System;
+global using System.Collections.Generic;
+global using System.Linq;
+global using System.Threading.Tasks;
+global using TUnit.Core;
+global using Moq;
+global using FluentAssertions;
+global using Bunit;
+global using Bunit.TestDoubles;
+global using Microsoft.Extensions.DependencyInjection;
+global using Reqnroll;
+```
 
+### TUnit Tests (Unit Testing)
+```csharp
 namespace ICTAce.FileHub.Tests.Unit
 {
     [TestClass]
@@ -189,14 +199,6 @@ namespace ICTAce.FileHub.Tests.Unit
 
 ### BUnit Tests (Blazor Component Testing)
 ```csharp
-using Bunit;
-using Bunit.TestDoubles;
-using FluentAssertions;
-using Microsoft.Extensions.DependencyInjection;
-using Moq;
-using ICTAce.FileHub.Client.Modules.FileHub;
-using ICTAce.FileHub.Shared.Models;
-
 namespace ICTAce.FileHub.Tests.Components
 {
     public class FileListComponentTests : TestContext
@@ -404,10 +406,6 @@ Scenario Outline: Validate file upload restrictions
 ```
 
 ```csharp
-using Reqnroll;
-using FluentAssertions;
-using ICTAce.FileHub.Tests.Drivers;
-
 namespace ICTAce.FileHub.Tests.Steps
 {
     [Binding]