chore: migrate .NET 6/8 projects to .NET 9

[devin-ai-integration]

Summary

Migrates all modern .NET projects (17 .csproj files) from .NET 6.0 and .NET 8.0 to .NET 9.0. This includes ASP.NET Core web apps, Blazor WASM/Server apps, WPF, and WinForms projects.

.NET Framework 4.x projects (in AspNet4/, Wpf/EqDemoWpfNet4/, WinForms/EqDemoWinFormsNet4/) were intentionally left unchanged — they require a separate migration approach.

Changes Made

TargetFramework updates (17 projects):

• 10 projects: net6.0 → net9.0 (Vue2, Vue3, React, Stencil, Blazor×4, WPF, WinForms)
• 7 projects: net8.0 → net9.0 (Angular×2, Razor×5)
• WPF/WinForms: net6.0-windows → net9.0-windows

NuGet package version upgrades:

Package	Old Version(s)	New Version
Microsoft.EntityFrameworkCore.*	6.0.1 / 8.0.2–8.0.5	9.0.16
Microsoft.AspNetCore.* (Identity, SpaProxy, Components, etc.)	6.0.1 / 8.0.2–8.0.5	9.0.16
Microsoft.Extensions.Http	6.0.0	9.0.16
Microsoft.Data.SqlClient	2.1.7 / 5.2.0	7.0.1
Microsoft.Data.Sqlite.Core	6.0.1	9.0.16
Microsoft.IdentityModel.JsonWebTokens	6.34.0 / 7.5.1	8.18.0
System.IdentityModel.Tokens.Jwt	6.34.0 / 7.5.1	8.18.0
System.Drawing.Common	4.7.2–4.7.3 / 8.0.4	9.0.16
Microsoft.VisualStudio.Web.CodeGeneration.Design	6.0.1	9.0.12
NuGet.Common / NuGet.Protocol	5.11.5	7.6.0
Microsoft.AspNetCore.ApiAuthorization.IdentityServer	6.0.1	7.0.20 (latest available — discontinued after .NET 7)

Third-party packages kept at current versions: Korzh.EasyQuery.* (7.4.0), EasyData.Exporters.* (1.5.9), VueCliMiddleware (6.0.0), Newtonsoft.Json (13.0.3), System.Data.SqlClient (4.8.6)

Other changes:

• Updated README.md prerequisites: .NET Core 2.0 → .NET 9.0 SDK
• Updated AspNetCore/Angular/AdHocReporting/README.md: ASP.NET Core 8.0 → 9.0
• Updated actions/checkout@v3 → v4 in CI workflow

Build Verification

All projects built successfully on Linux with .NET 9 SDK 9.0.314:

• 15 ASP.NET Core projects: 0 errors (pre-existing nullability warnings only)
• WPF + WinForms: Build with EnableWindowsTargeting=true — 0 errors
• RazorTypeScript.AdHocReporting: .NET restore/compile succeeds; npm pre-build step (rollup) fails — pre-existing issue on master branch (not related to this migration)

Known CI Expectations

• Snyk checks will fail — this is a known org-level Snyk policy issue that blocks all dependency-changing PRs (COG-GTM organization policy). See org Snyk config.
• No EF Core migrations exist in the migrated projects — no migration ID preservation concerns.

Review & Testing Checklist for Human

• Verify the WPF and WinForms projects build and run on a Windows machine with .NET 9 SDK
• Verify the Microsoft.AspNetCore.ApiAuthorization.IdentityServer (v7.0.20) still works correctly with .NET 9 in the BlazorWasm Server project — this package was discontinued and 7.0.20 is the last release
• Spot-check one or two ASP.NET Core projects by running dotnet run and verifying the web UI loads (requires EasyQuery license key in appsettings.json)
• If the RazorTypeScript npm build issue needs fixing, investigate the rollup config separately (pre-existing issue)

Notes

• The CI workflow (archive2cdn.yml) only archives and uploads to FTP — it doesn't build .NET projects, so no .NET SDK version reference needed there. Updated actions/checkout from v3 to v4.
• No Dockerfiles or global.json exist in this repository.
• No EF Core migrations exist in any of the migrated projects (migrations only exist in AspNet4/ which was not touched).

Link to Devin session: https://app.devin.ai/sessions/c0a0fdedd5dc4df29ceeb052241e0e8c
Requested by: @joao-cognition

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