fix: harden pi maintenance lifecycle

tools/thothctl/internal/pi/process_windows.go

@@ -0,0 +1,14 @@
+//go:build windows
+
+package pi
+
+import "golang.org/x/sys/windows"
+
+func processAlive(pid int) bool {
+	handle, err := windows.OpenProcess(windows.PROCESS_QUERY_LIMITED_INFORMATION, false, uint32(pid))
+	if err != nil { return err == windows.ERROR_ACCESS_DENIED }
+	defer windows.CloseHandle(handle)
+	var code uint32
+	if windows.GetExitCodeProcess(handle, &code) != nil { return true }
+	return code == 259 // STILL_ACTIVE
+}