[WIP] Fix WSL gateway validation tray output path discovery

[Copilot]

Thanks for asking me to work on this. I will get started on it and keep this PR's description up to date as I form a plan and make progress.

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This section details on the original issue you should resolve

<issue_title>Fix WSL gateway validation tray output path discovery</issue_title>
<issue_description>## Summary

validate-wsl-gateway.ps1 still appears to hardcode an old tray output target framework path:

src\OpenClaw.Tray.WinUI\bin\Debug\net10.0-windows10.0.19041.0\$runtimeIdentifier\OpenClaw.Tray.WinUI.exe

Current builds use the newer Windows TFM output path, so WSL validation can fail, launch stale output, or report misleading results.

Context

This was split out of #281. That older issue was originally framed as PR #274 validation blockers, but PR #274 has since merged and several original blockers appear fixed.

Acceptance criteria

• The validation script discovers or derives the actual tray build output path produced by the current project/build.
• -NoBuild fails clearly if the expected executable is missing or stale.
• The validation summary records the executable path and runtime identifier used.
• The old umbrella issue WSL local gateway onboarding validation blockers from PR #274 #281 can stay closed; any remaining WSL validation failures should get fresh focused issues with clean repros.</issue_description>

Comments on the Issue (you are @copilot in this section)

[shanselman]

@copilot is the solution at #434 not better than this?

[Copilot]

@copilot is the solution at #434 not better than this?

Yes — #434’s approach is better here. I updated this PR to use that pattern by deriving TargetFramework from OpenClaw.Tray.WinUI.csproj and building the tray exe path dynamically (commit 890c8f3).

[shanselman]

Closing this draft as superseded by #434, which used the same dynamic TargetFramework-from-csproj approach and has now been merged.

Thanks for checking this path and for confirming that #434 was the better base. Any remaining WSL validation failures should get fresh focused issues with repro details.

[shanselman]

Superseded by merged #434.