Skip duplicate GitHub package publishes

[ejsmith]

Summary

• check GitHub Packages for the computed MinVer package version before publishing
• skip publishing when that immutable version already exists
• preserve failures for missing versions when the actual publish command fails

Root cause

The main-branch CI run built and tested successfully, then failed publishing @foundatiofx/fetchclient@1.3.4-alpha.0.4 with E409 Cannot publish over existing version.

This applies the npm equivalent of the shared Foundatio .NET workflow's dotnet nuget push --skip-duplicate behavior. Package versions and tagged release behavior are unchanged.

Failed run: https://github.com/FoundatioFx/FetchClient/actions/runs/29471432936

Validation

• deno task format-check
• deno task lint
• deno task check
• deno task test (198 passed)
• exercised both shell branches: existing package skips; missing package publishes
• git diff --check

[chatgpt-codex-connector]

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