build(deps): bump ReactiveUI.Binding to 8.6.0

[glennawatson]

Summary

ReactiveUI now builds against ReactiveUI.Binding 8.6.0, which lets you ask an interaction as an observable again.

• BindingVersion in Directory.Packages.props is now 8.6.0.
• IInteraction<TInput, TOutput>.Handle(TInput) returns IObservable<TOutput>, as it did in ReactiveUI 24.
• Interaction<TInput, TOutput>.WhenHandled(TInput) returns the question as a cold observable.
• new Interaction<TInput, TOutput>(handlerScheduler) runs each handler on that scheduler, such as RxSchedulers.MainThreadScheduler.
• Interaction<TInput, TOutput>.Handle(TInput) still returns Task<TOutput>, so code written against 25.0.0 keeps compiling.

Why

Moving Interaction into ReactiveUI.Binding changed its API by accident in 25.0.0. Code upgrading from ReactiveUI 24 that subscribed to Handle, used it in an observable chain, or passed a handler scheduler stopped compiling. ReactiveUI.Binding 8.6.0 (reactiveui/ReactiveUI.Binding.SourceGenerators#151) restores it.

Breaking changes

None for code that uses or derives from Interaction<TInput, TOutput>. A class that implements IInteraction<TInput, TOutput> itself must implement Handle(TInput) returning IObservable<TOutput>. Nothing in this repository does.

How this was verified

Every Linux-runnable core test project passes on net10.0 against the released 8.6.0 packages.

• ReactiveUI.Tests (879), ReactiveUI.Tests.Reactive (881), ReactiveUI.AOT.Tests (39), ReactiveUI.Testing.Tests (57) and ReactiveUI.Builder.Tests (184) pass.
• The Windows-only and device projects are left to CI.

Checklist

• I have read the Contribute guide
• The PR title follows Conventional Commits
• Tests cover this change, or the summary says why they do not
• New or changed public API has XML documentation

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.69%. Comparing base (04209a0) to head (cab4e72).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4528      +/-   ##
==========================================
+ Coverage   93.64%   93.69%   +0.04%     
==========================================
  Files         175      175              
  Lines        6231     6231              
  Branches      743      743              
==========================================
+ Hits         5835     5838       +3     
+ Misses        395      392       -3     
  Partials        1        1              

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.