feat: Update to .net 10, nuget packages, C# 14.0

[BenjaminMichaelis]

No description provided.

[Copilot]

Pull request overview

Upgrades the solution to the .NET 10 / C# 14 toolchain and refreshes NuGet dependencies, with a few targeted code updates to accommodate framework/library API and analyzer changes.

Changes:

• Retarget projects from net9.0 to net10.0 and update LangVersion to 14.
• Update centralized package versions (ASP.NET, EF Core, Semantic Kernel, etc.).
• Adjust code for updated APIs/analyzers (ForwardedHeaders options, EF test DI overrides, OpenAI preview warning suppressions).

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
EssentialCSharp.Web/Program.cs	Updates forwarded headers configuration API usage for newer ASP.NET.
EssentialCSharp.Web/EssentialCSharp.Web.csproj	Retargets to net10.0 and suppresses CA1873 at the project level.
EssentialCSharp.Web.Tests/WebApplicationFactory.cs	Updates EF Core service removal strategy for test-time SQLite wiring.
EssentialCSharp.Web.Tests/EssentialCSharp.Web.Tests.csproj	Retargets test project to net10.0.
EssentialCSharp.Chat/EssentialCSharp.Chat.csproj	Retargets chat app to net10.0.
EssentialCSharp.Chat.Tests/EssentialCSharp.Chat.Tests.csproj	Retargets chat tests to net10.0.
EssentialCSharp.Chat.Shared/Services/AIChatService.cs	Adds OPENAI001 suppressions and updates Responses API tool creation call signature/usage.
EssentialCSharp.Chat.Shared/Extensions/ServiceCollectionExtensions.cs	Renames Postgres scope field and updates its usage.
EssentialCSharp.Chat.Shared/EssentialCSharp.Chat.Common.csproj	Retargets shared chat library to net10.0.
Directory.Packages.props	Updates central package versions for .NET 10 wave dependencies.
Directory.Build.props	Updates global language version to C# 14.