Fix build-and-release: replace softprops/action-gh-release with gh CLI upload

[Copilot]

softprops/action-gh-release@v2 fails with 404 Not Found on update-a-release-asset when a release for the tag already exists with a VSIX asset attached — the PATCH endpoint only updates asset metadata, not binary content, so overwriting via that path is broken.

Changes

• release.yml: Replace the softprops/action-gh-release@v2 upload step with gh release upload --clobber, which correctly handles both the "no release yet" and "release + asset already exist" cases

- name: Upload VSIX to release
  shell: pwsh
  run: |
    $tag  = "${{ steps.tag.outputs.tag }}"
    $vsix = "src/SsmsSqlFormatter/bin/Release/SsmsSqlFormatter.vsix"
    gh release view $tag 2>$null
    if ($LASTEXITCODE -ne 0) {
      gh release create $tag --title $tag --notes ""
    }
    gh release upload $tag $vsix --clobber
  env:
    GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}

--clobber deletes the stale asset and re-uploads rather than attempting a metadata-only PATCH, bypassing the broken code path entirely.