Use the TUN context snapshot in remaining launch-path reads (#9831)

Follow-up to #9830: audit of all TunModeItem.EnableTun usages found
three more launch-path reads of the live mutable config where the
behavior must agree with the context snapshot that generated the
config:

- CoreConfigClashService (mihomo custom config): the tun section was
  decided from the live config while the mihomo launch elevation uses
  the snapshot; a mid-reload toggle could produce a config containing
  tun launched without sudo, the same failure fixed in #9830. The tun
  state is now passed in as a snapshot.
- CoreManager.LoadCore: the Windows RemoveTunDevice cleanup now checks
  the main/pre context snapshots.
- CoreManager.WaitForProxyPort: preContext.AppConfig is a shared live
  reference; use preContext.IsTunEnabled instead.

Reads that intentionally stay live: StatusBarViewModel (UI state
source), CoreConfigContextBuilder (the snapshot capture point),
GetPreSocksItem (called during snapshot construction, self-consistent),
and AppManager.StatePort2 (transient mid-reload skew only, self-heals
after reload).

v2rayN/ServiceLib/Handler/CoreConfigHandler.cs

@@ -17,7 +17,7 @@ public static class CoreConfigHandler
         {
             result = node.CoreType switch
             {
-                ECoreType.mihomo => await new CoreConfigClashService(config).GenerateClientCustomConfig(node, fileName),
+                ECoreType.mihomo => await new CoreConfigClashService(config, context.IsTunEnabled).GenerateClientCustomConfig(node, fileName),
                 _ => await GenerateClientCustomConfig(node, fileName)
             };
         }

v2rayN/ServiceLib/Manager/CoreManager.cs

@@ -85,7 +85,7 @@ public class CoreManager
         await CoreStop();
         await Task.Delay(100);
 
-        if (Utils.IsWindows() && _config.TunModeItem.EnableTun)
+        if (Utils.IsWindows() && (mainContext?.IsTunEnabled == true || preContext?.IsTunEnabled == true))
         {
             await Task.Delay(100);
             await WindowsUtils.RemoveTunDevice();
@@ -222,7 +222,7 @@ public class CoreManager
         {
             return;
         }
-        if (!preContext.AppConfig.TunModeItem.EnableTun)
+        if (!preContext.IsTunEnabled)
         {
             return;
         }

v2rayN/ServiceLib/Services/CoreConfig/CoreConfigClashService.cs

@@ -1,9 +1,11 @@
 namespace ServiceLib.Services.CoreConfig;
 
 /// <summary>
-/// Core configuration file processing class
+/// Core configuration file processing class.
+/// The TUN state is taken as a snapshot so the generated config always agrees
+/// with the launch elevation decision (see CoreManager.ShouldRunAsSudo).
 /// </summary>
-public class CoreConfigClashService(Config config)
+public class CoreConfigClashService(Config config, bool isTunEnabled)
 {
     private static readonly string _tag = "CoreConfigClashService";
 
@@ -102,7 +104,7 @@ public class CoreConfigClashService(Config config)
             }
 
             //enable tun mode
-            if (config.TunModeItem.EnableTun)
+            if (isTunEnabled)
             {
                 var tun = EmbedUtils.GetEmbedText(Global.ClashTunYaml);
                 if (tun.IsNotEmpty())
@@ -171,7 +173,7 @@ public class CoreConfigClashService(Config config)
         }
         foreach (var item in mixinContent)
         {
-            if (!config.TunModeItem.EnableTun && item.Key == "tun")
+            if (!isTunEnabled && item.Key == "tun")
             {
                 continue;
             }