Fix Windows smoke: convert MSYS2 POSIX paths for native binary

MSYS2 mktemp returns /tmp/tmp.XXX but the Windows binary can't resolve
POSIX paths. Use cygpath -m to convert to C:/msys64/tmp/tmp.XXX which
works in both MSYS2 shell and Windows file APIs.

Author: DeusData

scripts/smoke-test.sh

@@ -11,6 +11,10 @@ set -euo pipefail
 
 BINARY="${1:?usage: smoke-test.sh <binary-path>}"
 TMPDIR=$(mktemp -d)
+# On MSYS2/Windows, convert POSIX path to native Windows path for the binary
+if command -v cygpath &>/dev/null; then
+    TMPDIR=$(cygpath -m "$TMPDIR")
+fi
 trap 'rm -rf "$TMPDIR"' EXIT
 
 CLI_STDERR=$(mktemp)