Implement new Go based Desktop app

This focuses on Windows first, but coudl be used for Mac
and possibly linux in the future.

app/lifecycle/getstarted_windows.go

@@ -0,0 +1,44 @@
+package lifecycle
+
+import (
+	"fmt"
+	"log/slog"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"syscall"
+)
+
+func GetStarted() error {
+	const CREATE_NEW_CONSOLE = 0x00000010
+	var err error
+	bannerScript := filepath.Join(AppDir, "ollama_welcome.ps1")
+	args := []string{
+		// TODO once we're signed, the execution policy bypass should be removed
+		"powershell", "-noexit", "-ExecutionPolicy", "Bypass", "-nologo", "-file", bannerScript,
+	}
+	args[0], err = exec.LookPath(args[0])
+	if err != nil {
+		return err
+	}
+
+	// Make sure the script actually exists
+	_, err = os.Stat(bannerScript)
+	if err != nil {
+		return fmt.Errorf("getting started banner script error %s", err)
+	}
+
+	slog.Info(fmt.Sprintf("opening getting started terminal with %v", args))
+	attrs := &os.ProcAttr{
+		Files: []*os.File{os.Stdin, os.Stdout, os.Stderr},
+		Sys:   &syscall.SysProcAttr{CreationFlags: CREATE_NEW_CONSOLE, HideWindow: false},
+	}
+	proc, err := os.StartProcess(args[0], args, attrs)
+
+	if err != nil {
+		return fmt.Errorf("unable to start getting started shell %w", err)
+	}
+
+	slog.Debug(fmt.Sprintf("getting started terminal PID: %d", proc.Pid))
+	return proc.Release()
+}