Update to .NET 9 and remove Swashbuckle

[Copilot]

This PR updates the entire project from .NET 8 to .NET 9, including all project files, NuGet packages, and CI/CD pipeline configurations. Additionally, Swashbuckle has been completely removed from the project.

Changes Made

Project Files

• Updated TargetFramework from net8.0 to net9.0 in both the main web project and test project

NuGet Packages

Updated test project dependencies to .NET 9 compatible versions:

• Microsoft.AspNetCore.Mvc.Testing: 8.0.0 → 9.0.0
• Microsoft.NET.Test.Sdk: 17.8.0 → 17.12.0
• xunit: 2.6.1 → 2.9.2
• xunit.runner.visualstudio: 2.5.3 → 2.8.2

CI/CD Pipeline

• Updated GitHub Actions workflow to use .NET 9.0.x
• Updated actions/setup-dotnet from v3 to v4

Swashbuckle Removal

• Removed Swashbuckle.AspNetCore package reference
• Deleted SwaggerConfigurator.cs and the entire Swagger feature directory
• Removed all Swagger-related middleware configuration from Startup.cs

Testing

All 9 existing tests pass successfully with .NET 9 in both Debug and Release configurations, confirming no breaking changes were introduced by the upgrade or Swashbuckle removal.

Fixes #2

Original prompt

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This section details on the original issue you should resolve

<issue_title>Update to .NET 9</issue_title>
<issue_description>* Update all code to use .NET 9

• Update pipelines etc to use .NET 9</issue_description>

Comments on the Issue (you are @copilot in this section)

Fixes #2

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✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.

[joseftw]

@copilot Remove Swashbuckle completely.

[Copilot]

@copilot Remove Swashbuckle completely.

Removed Swashbuckle completely. The changes include:

• Removed Swashbuckle.AspNetCore package reference from the project file
• Deleted the SwaggerConfigurator.cs file and the entire Swagger feature directory
• Removed all Swagger-related code from Startup.cs (using statement, ConfigureSwaggerFeature(), UseSwagger(), and UseSwaggerUI())

All tests still pass. (commit: TBD)