ui: avoid hangs (systemd-run no-block + timeouts for systemctl)

selective-vpn-gui/traffic_mode_dialog.py

@@ -917,13 +917,27 @@ RU: Применяет policy-rules и проверяет health. При оши
             "systemd-run",
             "--user",
             "--scope",
+            "--no-block",
             "--unit",
             unit,
             "--collect",
             "--same-dir",
         ] + args
 
-        p = subprocess.run(run_cmd, capture_output=True, text=True, check=False)
+        try:
+            p = subprocess.run(
+                run_cmd,
+                capture_output=True,
+                text=True,
+                check=False,
+                timeout=6,
+            )
+        except subprocess.TimeoutExpired as e:
+            raise RuntimeError(
+                "systemd-run timed out (UI would freeze without this guard). "
+                "Try again or verify that systemd --user is responsive.\n\n"
+                f"command: {' '.join(run_cmd)}"
+            ) from e
         out = ((p.stdout or "") + (p.stderr or "")).strip()
         if p.returncode != 0:
             raise RuntimeError(f"systemd-run failed: {p.returncode}\n{out}".strip())
@@ -1154,14 +1168,19 @@ RU: Применяет policy-rules и проверяет health. При оши
         return ""
 
     def _systemctl_user(self, args: list[str]) -> tuple[int, str]:
+        cmd = ["systemctl", "--user"] + list(args or [])
+        try:
             p = subprocess.run(
-            ["systemctl", "--user"] + list(args or []),
+                cmd,
                 capture_output=True,
                 text=True,
                 check=False,
+                timeout=4,
             )
             out = ((p.stdout or "") + (p.stderr or "")).strip()
             return int(p.returncode or 0), out
+        except subprocess.TimeoutExpired:
+            return 124, f"timeout running: {' '.join(cmd)}"
 
     def _list_running_svpn_scopes(self) -> list[str]:
         code, out = self._systemctl_user(