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-git-lfs.sh

@@ -4,12 +4,18 @@ set -euo pipefail
 
 root=$(cd "$(dirname "$0")/.." && pwd)
 exec_dir=$root/engines/git/libexec/git-core
+git=$root/engines/git/bin/git
+exe=
 version=v3.8.0
 case "$(uname -s)-$(uname -m)" in
   Darwin-arm64) asset=git-lfs-darwin-arm64-$version.zip sum=caff76a7d070d8160c89bc39b6e85d98f24135b6fed038a3b4de2590d25102d8 ;;
   Darwin-x86_64) asset=git-lfs-darwin-amd64-$version.zip sum=f1c17aeca0b4eaab9ea606226477dbed3b84b56fe0811a9f967d2ea2b2393c53 ;;
   Linux-x86_64) asset=git-lfs-linux-amd64-$version.tar.gz sum=e455e00f15d9b95661b8d53498ffb0c3367962cf1ec73c31ab7369516cd6ab8d ;;
   Linux-aarch64) asset=git-lfs-linux-arm64-$version.tar.gz sum=ac9c8efac980bb0505ead384d087e2acb6486fd8498691a2165fa174ec6118c2 ;;
+  MINGW*-x86_64 | MSYS*-x86_64)
+    asset=git-lfs-windows-amd64-$version.zip sum=b62e7b8ceddee635f691233d77de8eaa4b213e9209e0173811d8cfa77f7882c1
+    exec_dir=$root/engines/git/ucrt64/libexec/git-core git=$root/engines/git/cmd/git.exe exe=.exe
+    ;;
   *) echo "fetch-git-lfs: no pinned build for $(uname -s)-$(uname -m)" >&2; exit 1 ;;
 esac
 [ -d "$exec_dir" ] || { echo "fetch-git-lfs: build Git first (scripts/build-git.sh)" >&2; exit 1; }
@@ -25,7 +31,7 @@ case "$asset" in
   *.zip) unzip -q "$work/$asset" -d "$work/x" ;;
   *) mkdir "$work/x" && tar -xzf "$work/$asset" -C "$work/x" ;;
 esac
-install -m 755 "$(find "$work/x" -type f -name git-lfs | head -1)" "$exec_dir/git-lfs"
+install -m 755 "$(find "$work/x" -type f -name "git-lfs$exe" | head -1)" "$exec_dir/git-lfs$exe"
 # The archive has no licence; the tag's own, checked.
 curl -fsSL -o "$work/LICENSE.md" "https://raw.githubusercontent.com/git-lfs/git-lfs/$version/LICENSE.md"
 got=$(shasum -a 256 "$work/LICENSE.md" | cut -d' ' -f1)
@@ -35,4 +41,4 @@ got=$(shasum -a 256 "$work/LICENSE.md" | cut -d' ' -f1)
 }
 mkdir -p "$root/engines/git/share/doc/git-lfs"
 install -m 644 "$work/LICENSE.md" "$root/engines/git/share/doc/git-lfs/LICENSE.md"
-"$root/engines/git/bin/git" lfs version
+"$git" lfs version