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)
             };
         }