Fix framework-dependent release archive publication

[uniblab]

Resolve the six RID archive failures from release workflow run 33737000982.

The NuGet package path succeeded: Icod.LineEditor.Tools 1.1.0 was selected and published to both NuGet.org and GitHub Packages. All six archive jobs failed while publishing the lineeditor router because its project references (ed, red, and sed) were evaluated as self-contained executables while the router was being published framework-dependent, producing NETSDK1151.

This PR:

• centralizes the intended framework-dependent distribution contract with <SelfContained>false</SelfContained> in Directory.Build.props;
• passes -p:SelfContained=false explicitly through BuildReleaseArchive.ps1 so the property propagates through router project references during RID publication;
• keeps framework-dependent single-file archive output unchanged;
• adds a Linux x64 archive-construction smoke step to PR Staging validation so this release-only path is exercised before tagging.

No command behavior, package identity, or package version is changed.