Implement core diagnostic memory layer, execution helpers, and high-level facade slices

Implemented:
- Core: UTF-16 ReadString boundary/alignment fix, target bitness and process id on MemoryBase
- function interception: PatchManager, DetourManager, InstructionAnalyzer, MainThreadDispatcher
- Execution: BackgroundTaskExecutor, InProcessInvoker
- High-level: Magic facade, RemotePointer, async wrappers
- Discovery/external code loading/Window groundwork (PEB/TEB, pattern scanning, raw allocations, DLL external code loading, window/input)

Tests: 180 passing, 4 integration/interactive tests skipped.

WhiteMagic/ExternalReader.cs

@@ -1,4 +1,5 @@
 using System.Diagnostics;
+using Process = System.Diagnostics.Process;
 using System.Runtime.InteropServices;
 using WhiteMagic.Native;
 
@@ -13,6 +14,8 @@ public sealed class ExternalReader : MemoryBase
 {
     private readonly SafeMemoryHandle _handle;
     private readonly IntPtr _imageBase;
+    private readonly bool _is64Bit;
+    private readonly int _processId;
     private bool _disposed;
 
     /// <summary>
@@ -31,16 +34,27 @@ public sealed class ExternalReader : MemoryBase
     /// <param name="process">The target process.</param>
     /// <param name="desiredAccess">The access rights to request. Defaults to
     /// <see cref="DefaultAccess"/>.</param>
-    public ExternalReader(Process process, ProcessAccess desiredAccess = DefaultAccess)
+    public ExternalReader(System.Diagnostics.Process process, ProcessAccess desiredAccess = DefaultAccess)
     {
-        _handle = NativeMethods.OpenProcess(desiredAccess, false, process.Id);
+        _processId = process.Id;
+        _handle = NativeMethods.OpenProcess(desiredAccess, false, _processId);
         if (_handle.IsInvalid)
         {
             int error = Marshal.GetLastPInvokeError();
             throw new InvalidOperationException(
-                $"OpenProcess failed for PID {process.Id}: error {error}");
+                $"OpenProcess failed for PID {_processId}: error {error}");
         }
 
+        // Derive target bitness. A 64-bit host sees a 32-bit target as WOW64.
+        // A 32-bit host can only open 32-bit targets. If the API fails, fall
+        // back to the current process bitness (self-open path).
+        if (!NativeMethods.IsWow64Process(_handle, out bool wow64))
+        {
+            wow64 = false;
+        }
+
+        _is64Bit = Environment.Is64BitProcess && !wow64;
+
         // Process.MainModule throws Win32Exception for a bitness-mismatched or protected
         // target. A missing image base must not sink the whole reader — callers can still
         // use absolute addresses when ImageBase is unknown.
@@ -60,6 +74,12 @@ public sealed class ExternalReader : MemoryBase
     /// <inheritdoc />
     public override SafeMemoryHandle Handle => _handle;
 
+    /// <inheritdoc />
+    public override bool Is64Bit => _is64Bit;
+
+    /// <inheritdoc />
+    public override int ProcessId => _processId;
+
     /// <inheritdoc />
     public override byte[] ReadBytes(IntPtr address, int count, bool isRelative = false)
     {
@@ -84,7 +104,7 @@ public sealed class ExternalReader : MemoryBase
         if (!_disposed)
         {
             _disposed = true;
-            _handle.Dispose();
+            base.Dispose();
         }
     }
 }