Use upload-artifact v7 to publish VSIX directly (non-zipped)

[Copilot]

GitHub Actions now supports uploading single files as artifacts without ZIP wrapping. This makes .vsix files directly downloadable and installable from the Actions run page — no unzipping required.

Changes

• upload-artifact@v4 → @v7 on both upload steps
• archive: false on the VSIX upload — file is stored as-is, filename becomes the artifact name
• Rename step added before upload to append the OS name (e.g., powershell-2024.5.0-ubuntu-latest.vsix), since archive: false derives artifact name from filename and all three matrix jobs would otherwise conflict
• if-no-files-found: ignore added so the upload step is a no-op on build failures
• name: parameter removed from VSIX upload (ignored when archive: false)

- name: Rename VSIX to include OS name
  if: always()
  shell: pwsh
  # archive: false uses the filename as the artifact name, so we need unique names across matrix jobs
  run: Get-Item out/*.vsix -ErrorAction SilentlyContinue | Rename-Item -NewName { $_.BaseName + '-${{ matrix.os }}' + $_.Extension }
  working-directory: vscode-powershell

- name: Upload build artifacts
  uses: actions/upload-artifact@v7
  if: always()
  with:
    # archive: false uploads the .vsix directly (no zip wrapper) using the filename as the artifact name
    path: "vscode-powershell/out/*.vsix"
    archive: false
    if-no-files-found: ignore