Upgrade Windows TFM to Windows 11 (net10.0-windows10.0.22621.0)

[indcoder]

Summary

Current MAUI project files (for example Visage.FrontEnd/Visage.FrontEnd.csproj) target a Windows TFM of net9.0-windows10.0.19041.0. As part of the planned migration to .NET 10 we should also offer an option to update the Windows Target Framework Moniker to the Windows 11 equivalent (for example net10.0-windows10.0.22621.0).

Rationale

• 19041 corresponds to Windows 10 20H1 (May 2020). Bumping to 22621 targets Windows 11 and unlocks newer platform APIs and improved tooling support.
• Moving to net10.0-windows10.0.22621.0 aligns with upgrading the solution to .NET 10 and modernizing platform targets for MAUI desktop builds.
• This is optional for backwards compatibility; keeping 19041 is still supported if we want to preserve older Windows support.

Acceptance criteria

• Add a decision or PR that updates the Windows TFM in MAUI projects to net10.0-windows10.0.22621.0 (or documents the choice to keep 19041).
• Update SupportedOSPlatformVersion and TargetPlatformMinVersion for Windows in the same project files to 10.0.22621.0.
• CI/build images and developer setup documentation updated if newer SDKs/workloads are required.
• A PR is created that updates the Visage.FrontEnd.csproj (and any other affected projects) and successfully builds on the CI.

Implementation steps

1. Search repository for occurrences of net9.0-windows10.0.19041.0, net9.0-, and Windows min versions like 10.0.17763.0.
2. Update TargetFrameworks in Visage.FrontEnd.csproj:
   • net9.0-android;net9.0-ios;net9.0-maccatalyst -> net10.0-android;net10.0-ios;net10.0-maccatalyst
   • net9.0-windows10.0.19041.0 -> net10.0-windows10.0.22621.0
3. Update the Windows SupportedOSPlatformVersion and TargetPlatformMinVersion to 10.0.22621.0.
4. Update global.json if pinning SDK versions to use a .NET 10 SDK.
5. Update MAUI/other package references if necessary to versions compatible with .NET 10.
6. Run dotnet build on CI (or locally) and fix any API/package compatibility issues.

Notes

• This issue is primarily tech-debt/upgrade work and may be split into smaller PRs: one to update TFMs, another to update CI and docs, and a follow-up to address compatibility issues.
• If we want to keep broader Windows 10 compatibility, we can instead change the TFM to net10.0-windows10.0.19041.0 and only bump the SupportedOSPlatformVersion when platform APIs are required.