fix: include go.sum in installation to fix analyze/status build

Fixes #316 - The go.sum file was missing from the install file list,
causing 'missing go.sum entry' errors when trying to build the Go
tools (analyze, status) on systems without pre-built binaries.

install.ps1

@@ -258,6 +258,7 @@ function Install-Mole {
     $filesToCopy = @(
         "mole.ps1"
         "go.mod"
+        "go.sum"
         "bin"
         "lib"
         "cmd"