Fix: make AutoRelog retries single-owner (#3186)

Login rejections could schedule and execute multiple restarts for one failure while leaving no usable console route during reconnect delays.

Changes:
- Bind failure and restart work to immutable connection attempts
- Coalesce automatic retries while allowing explicit settings replacement until commit
- Preserve held bots and offline command routing across failed logins
- Add deterministic retry, ownership, and routing regression tests

Fixes #3186

MinecraftClient/ConnectionAttemptLifecycle.cs

@@ -0,0 +1,107 @@
+using System;
+using System.Collections.Generic;
+using System.Threading;
+using MinecraftClient.Scripting;
+
+namespace MinecraftClient
+{
+    internal sealed class ConnectionAttemptLifecycle
+    {
+        private int disconnectState;
+
+        internal bool IsFailureClaimed => Volatile.Read(ref disconnectState) != 0;
+
+        internal bool TryBeginDisconnect()
+        {
+            return Interlocked.CompareExchange(ref disconnectState, 1, 0) == 0;
+        }
+
+        internal void CompleteDisconnect()
+        {
+            Volatile.Write(ref disconnectState, 2);
+        }
+
+        internal static void RestoreHeldBots(ICollection<ChatBot> heldBots, Action<ChatBot> loadBot)
+        {
+            ArgumentNullException.ThrowIfNull(heldBots);
+            ArgumentNullException.ThrowIfNull(loadBot);
+
+            foreach (ChatBot bot in heldBots)
+                loadBot(bot);
+            heldBots.Clear();
+        }
+    }
+
+    internal sealed class AttemptOwnedRoute
+    {
+        private const long NoOwner = -1;
+        private readonly Lock stateLock = new();
+        private long ownerAttempt = NoOwner;
+
+        internal long OwnerAttempt
+        {
+            get
+            {
+                lock (stateLock)
+                    return ownerAttempt;
+            }
+        }
+
+        internal bool TryActivate(long connectionAttempt, Action activate)
+        {
+            ArgumentNullException.ThrowIfNull(activate);
+
+            lock (stateLock)
+            {
+                if (ownerAttempt >= connectionAttempt)
+                    return false;
+
+                ownerAttempt = connectionAttempt;
+                activate();
+                return true;
+            }
+        }
+
+        internal bool TryDeactivate(long connectionAttempt, Action deactivate)
+        {
+            ArgumentNullException.ThrowIfNull(deactivate);
+
+            lock (stateLock)
+            {
+                if (ownerAttempt != connectionAttempt)
+                    return false;
+
+                ownerAttempt = NoOwner;
+                deactivate();
+                return true;
+            }
+        }
+
+        internal bool TryTransfer(long sourceConnectionAttempt, long targetConnectionAttempt)
+        {
+            lock (stateLock)
+            {
+                if (ownerAttempt != sourceConnectionAttempt)
+                    return false;
+
+                ownerAttempt = targetConnectionAttempt;
+                return true;
+            }
+        }
+
+        internal bool TryDeactivate(Action deactivate)
+        {
+            ArgumentNullException.ThrowIfNull(deactivate);
+
+            lock (stateLock)
+            {
+                if (ownerAttempt == NoOwner)
+                    return false;
+
+                ownerAttempt = NoOwner;
+                deactivate();
+                return true;
+            }
+        }
+    }
+}