fix: use pwsh and \$true for release cleanup step in Windows build

The || operator and 'true' are bash idioms that don't work in Windows
PowerShell 5.1 (shell: powershell). Switch to pwsh (PowerShell 7)
which supports the || pipeline chain operator, and replace bare 'true'
with '$true' (PowerShell boolean literal).

https://claude.ai/code/session_015XDgrfp3HkuA7jyLE8gP5w

Author: claude

.github/workflows/build_windows.yml

@@ -38,9 +38,9 @@ jobs:
 
       - name: Delete existing latest release if exists
         run: |
-          gh release delete latest --yes 2>$null || true
-          git push origin :refs/tags/latest 2>$null || true
-        shell: powershell
+          gh release delete latest --yes 2>$null || $true
+          git push origin :refs/tags/latest 2>$null || $true
+        shell: pwsh
         env:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}