fix: resolve MINGW64 double-path conversion in install.sh (#1015)

On Git Bash (MINGW64), the native Windows Node.js binary receives a
POSIX path from $SCRIPT_DIR (e.g. /g/projects/everything-claude-code)
which Git Bash auto-converts to G:\g\projects\... — doubling the
drive letter prefix and producing MODULE_NOT_FOUND errors.

Fix: use `cygpath -w` when available to explicitly convert the POSIX
path to a proper Windows path before passing it to Node, falling back
to the original path on non-MSYS/Cygwin environments.

install.sh

@@ -20,4 +20,13 @@ if [ ! -d "$SCRIPT_DIR/node_modules" ]; then
     (cd "$SCRIPT_DIR" && npm install --no-audit --no-fund --loglevel=error)
 fi
 
-exec node "$SCRIPT_DIR/scripts/install-apply.js" "$@"
+# On MSYS2/Git Bash, convert the POSIX path to a Windows path so Node.js
+# (a native Windows binary) receives a valid path instead of a doubled one
+# like G:\g\projects\... that results from Git Bash's auto path conversion.
+if command -v cygpath &>/dev/null; then
+    NODE_SCRIPT="$(cygpath -w "$SCRIPT_DIR/scripts/install-apply.js")"
+else
+    NODE_SCRIPT="$SCRIPT_DIR/scripts/install-apply.js"
+fi
+
+exec node "$NODE_SCRIPT" "$@"