feat(ci): build and publish Windows installer executable in release workflows

[wgqqqqq]

Summary

Update CI workflows to build and publish the new Windows installer executable (bitfun-installer.exe) instead of the
old setup.exe output.

Changes

• In .github/workflows/desktop-package.yml and .github/workflows/nightly.yml:
  • Switch Windows build command:
    • npm run desktop:build:nsis -> npm run installer:build
  • Add Windows-only installer dependency install step:
    • npm --prefix BitFun-Installer ci
  • Add installer output to artifact collection:
    • BitFun-Installer/src-tauri/target/release/bitfun-installer.exe
  • Update release asset glob:
    • **/*setup.exe -> **/*bitfun-installer.exe

Impact

• Windows release/nightly pipelines now publish the new installer binary.
• macOS packaging logic remains unchanged.