Route TUI controls through polkit

src/fenris/tui.py

@@ -14,6 +14,7 @@ Criteria: TUI-1, TUI-2, TUI-4, CI-1, CI-2, CI-4, IN-3, LC-6, LC-8.
 """
 from __future__ import annotations
 
+import os
 import sqlite3
 import subprocess
 import sys
@@ -1454,6 +1455,8 @@ class FenrisTuiApp(App):
         cmd = [self.helper_path, operation]
         if extra_args:
             cmd.extend(extra_args)
+        if os.geteuid() != 0:
+            cmd.insert(0, "pkexec")
 
         try:
             with self.suspend():