Fix dispatcher crash/deadlock, instruction analyzer, cache equality, task leak, and redirection protection

- MainThreadDispatcher: guard DispatchHook with try/catch so exceptions never escape to native caller; drain and fault pending work on Dispose; synchronize Execute/ExecuteAsync/Dispose against race/dispose.
- InstructionAnalyzer: require ModRM 0xEC for 0x83/0x81 sub-esp/rsp forms, rejecting unsafe RIP-relative or memory forms.
- PatternScannerCache: implement value equality on CacheKey so repeated scans actually hit cache.
- BackgroundTaskExecutor: add remote allocations to the free list immediately after VirtualAllocEx, before any write that could fail and leak.
- redirect: capture and restore original page protection in Apply/Remove instead of leaving target RWX.
- Regression tests for all six fixes.

Tests: 198 passing, 4 integration/interactive skipped.

WhiteMagicTest/Hooking/HookingTests.cs

@@ -275,4 +275,64 @@ public class HookingTests
             NativeMethods.VirtualFreeEx(reader.Handle, allocation, 0, MemoryFreeType.Release);
         }
     }
+
+    [Fact]
+    public async Task MainThreadPump_dispose_faults_pending_work()
+    {
+        using var reader = CreateReader();
+
+        IntPtr targetPtr = AllocateFrameStub(reader, out IntPtr allocation);
+        try
+        {
+            var pump = new WhiteMagic.Execution.MainThreadPump(reader.DetourManager, targetPtr);
+            pump.Install();
+
+            Task<int> pending = pump.ExecuteAsync(() => 42);
+
+            pump.Dispose();
+
+            var ex = await Assert.ThrowsAsync<ObjectDisposedException>(() => pending);
+            Assert.Equal(nameof(WhiteMagic.Execution.MainThreadPump), ex.ObjectName);
+        }
+        finally
+        {
+            NativeMethods.VirtualFreeEx(reader.Handle, allocation, 0, MemoryFreeType.Release);
+        }
+    }
+
+    [Fact]
+    public async Task MainThreadPump_dispose_while_execute_blocked_does_not_deadlock()
+    {
+        using var reader = CreateReader();
+
+        IntPtr targetPtr = AllocateFrameStub(reader, out IntPtr allocation);
+        try
+        {
+            var pump = new WhiteMagic.Execution.MainThreadPump(reader.DetourManager, targetPtr);
+            pump.Install();
+
+            // Start Execute on another thread; it will block until Dispose drains the queue.
+            Task executeTask = Task.Run(() =>
+            {
+                try
+                {
+                    pump.Execute<int>(() => 42);
+                }
+                catch (ObjectDisposedException)
+                {
+                }
+            });
+
+            // Give Execute time to pass the gate and block on the TCS.
+            await Task.Delay(50);
+            pump.Dispose();
+
+            Task completed = await Task.WhenAny(executeTask, Task.Delay(TimeSpan.FromSeconds(2)));
+            Assert.Same(executeTask, completed);
+        }
+        finally
+        {
+            NativeMethods.VirtualFreeEx(reader.Handle, allocation, 0, MemoryFreeType.Release);
+        }
+    }
 }