Fix run-app-local build argument forwarding

[shanselman]

Summary

• Fixes run-app-local.ps1 so its default build path forwards Configuration to build.ps1 by name instead of accidentally binding -Configuration as the positional Project argument.
• Keeps -Dev forwarding explicit through the existing DevBuild switch.
• Updates the existing source-contract test that guards local launcher identity wiring.

Validation

• dotnet test .\tests\OpenClaw.Tray.Tests\OpenClaw.Tray.Tests.csproj --no-restore --filter "FullyQualifiedName~LocalInstallerBuild_UsesOneIdentitySwitchAndValidatesPayloadMarker" — passed: 1.
• .\run-app-local.ps1 -DryRun -Configuration Debug — passed after stopping the previously launched tray process that locked the output assembly.
• .\build.ps1 — passed.
• dotnet test .\tests\OpenClaw.Shared.Tests\OpenClaw.Shared.Tests.csproj --no-restore — passed: 2703 passed / 31 skipped.
• dotnet test .\tests\OpenClaw.Tray.Tests\OpenClaw.Tray.Tests.csproj --no-restore — passed: 1584 passed.

Real behavior proof

• run-app-local.ps1 default build path now invokes build.ps1 successfully without mis-binding -Configuration.
• Non-isolated release/default local launch from main succeeded after the fix.