Windows and Linux build environments; check clean on both (E-01)

MuPDF builds with MSBuild on Windows (/MT, OpenSSL from vcpkg);
Git for Windows' MinGit stands in for the source build there. CEF
loads from where libcef lives and sets its API version first on
every platform. File identity on Windows compares volume and index.
The checkout and reference/ keep LF on Windows.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

scripts/fetch-references.sh

@@ -21,6 +21,9 @@ fetch() { # name url rev [sparse paths...]
   fi
   rm -rf "$dir"
   git init -q "$dir"
+  # Upstream bytes, whatever the host's line-ending setting.
+  git -C "$dir" config core.autocrlf false
+  git -C "$dir" config core.eol lf
   git -C "$dir" remote add origin "$url"
   if [ $# -gt 0 ]; then
     git -C "$dir" sparse-checkout init --cone