refactor(app): remove unsupported runtime and UI state

lib/logic/power_settings.dart

@@ -1,13 +1,7 @@
 import 'package:flutter/foundation.dart';
 import 'package:flutter/services.dart';
 
-/// Background-survival controls.
-///
-/// Android stops background services of apps that are not exempt from Doze and
-/// App Standby, and it tears down the whole process group when a task is swiped
-/// away. Those are OS behaviours, not app bugs; the battery-optimisation
-/// exemption is the one sanctioned way an app can ask for around them, and it
-/// still needs one user tap.
+/// Android background-survival controls that ReVolt can actually verify.
 abstract final class PowerSettings {
   PowerSettings._();
 
@@ -15,7 +9,6 @@ abstract final class PowerSettings {
     'com.revoltvpn.app/power',
   );
 
-  /// Whether the OS has exempted this app from Doze / App Standby.
   static Future<bool> isBatteryOptimisationDisabled() async {
     if (kIsWeb) return true;
     try {
@@ -28,8 +21,6 @@ abstract final class PowerSettings {
     }
   }
 
-  /// Shows the system exemption dialog. Returns false only when no system UI
-  /// could be opened at all — a user declining still returns true.
   static Future<bool> requestDisableBatteryOptimisation() async {
     if (kIsWeb) return true;
     try {
@@ -41,53 +32,4 @@ abstract final class PowerSettings {
       return false;
     }
   }
-
-  /// Whether the VPN runtime is genuinely alive.
-  ///
-  /// The Xray service runs in a separate process, so nothing it stores in
-  /// statics is visible to us. This asks the OS instead: is our service process
-  /// running, and (for TUN) is there an active VPN transport?
-  static Future<VpnRuntimeState> runtimeState() async {
-    if (kIsWeb) return const VpnRuntimeState(processAlive: false, vpnTransport: false);
-    try {
-      final result = await _channel.invokeMapMethod<String, dynamic>(
-        'isVpnRuntimeAlive',
-      );
-      return VpnRuntimeState(
-        processAlive: result?['processAlive'] == true,
-        vpnTransport: result?['vpnTransport'] == true,
-      );
-    } catch (_) {
-      return const VpnRuntimeState(processAlive: false, vpnTransport: false);
-    }
-  }
-
-  /// Pushes the absolute session-expiry timestamp (epoch ms) to the VPN
-  /// service so it can tear the tunnel down even when the UI process is gone.
-  static Future<void> setSessionExpiry(int expiresAtMs) async {
-    if (kIsWeb) return;
-    try {
-      await _channel.invokeMethod<void>('setSessionExpiry', {
-        'expiresAtMs': expiresAtMs,
-      });
-    } catch (_) {
-      // Best-effort. The daemon also keeps its last persisted expiry.
-    }
-  }
-}
-
-@immutable
-class VpnRuntimeState {
-  final bool processAlive;
-  final bool vpnTransport;
-
-  const VpnRuntimeState({
-    required this.processAlive,
-    required this.vpnTransport,
-  });
-
-  /// TUN needs both a live service and a real VPN interface. Proxy mode has no
-  /// VPN interface at all, so the service process is the whole signal.
-  bool aliveFor({required bool tunMode}) =>
-      processAlive && (!tunMode || vpnTransport);
 }