Initial sacred_re scaffold with borderless fullscreen mod

- Launcher (sacred_re.exe) starts sacred.exe with sacred_re.dll injected
  via Detours; the DLL verifies the Sacred Gold 2.28 build before hooking.
- Hook framework: RE_HOOK for game addresses, RE_HOOK_API for Windows
  APIs, per-hook enable/disable in sacred_re.ini, sacred_re.log.
- Game code: Log (0x66f1c0) hooked, CmdLineHasFlag (0x813140) rewritten.
- Borderless mod: forces windowed mode, covers the monitor, scales the
  1024x768 image aspect-correct, remaps mouse input, keeps running in the
  background with keyboard input hidden while unfocused.
- CMake/Ninja/MSVC x86 build, VS Code setup, disasm tool, function map.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

src/re/dllmain.cpp

@@ -0,0 +1,75 @@
+// sacred_re.dll entry point. Loaded into sacred.exe by the launcher before the
+// game's own entry point runs, so every hook is in place from the first
+// instruction of game code.
+
+#include <string>
+
+#include <windows.h>
+#include <detours.h>
+
+#include "re/config.h"
+#include "re/hook.h"
+#include "re/log.h"
+
+namespace {
+
+// The only build we support: Sacred Gold 2.28, sacred.exe
+// sha256 fe774c6f985b02c9ce03103c2e55e5d853258c0cc3c737ccd211219c74460cb9.
+// Every hook address in this project is specific to it.
+constexpr DWORD kExpectedTimestamp = 0x451BBE74;
+constexpr DWORD kExpectedSizeOfImage = 0x01999000;
+
+std::wstring ModuleDir(HMODULE module) {
+    wchar_t path[MAX_PATH];
+    DWORD length = GetModuleFileNameW(module, path, MAX_PATH);
+    std::wstring dir(path, length);
+    return dir.substr(0, dir.find_last_of(L"\\/") + 1);
+}
+
+bool IsSupportedGameBuild() {
+    auto base = reinterpret_cast<const BYTE*>(GetModuleHandleW(nullptr));
+    auto dos = reinterpret_cast<const IMAGE_DOS_HEADER*>(base);
+    auto nt = reinterpret_cast<const IMAGE_NT_HEADERS32*>(base + dos->e_lfanew);
+    re::Log("game image: timestamp 0x%08lx, size 0x%08lx", nt->FileHeader.TimeDateStamp,
+            nt->OptionalHeader.SizeOfImage);
+    return nt->FileHeader.TimeDateStamp == kExpectedTimestamp &&
+           nt->OptionalHeader.SizeOfImage == kExpectedSizeOfImage;
+}
+
+void Startup(HMODULE module) {
+    std::wstring dir = ModuleDir(module);
+    re::OpenLog((dir + L"sacred_re.log").c_str());
+    re::SetConfigPath(dir + L"sacred_re.ini");
+    re::Log("sacred_re loaded");
+
+    if (!IsSupportedGameBuild()) {
+        re::Log("unsupported sacred.exe build, no hooks installed");
+        MessageBoxW(nullptr,
+                    L"This sacred.exe is not the supported Sacred Gold 2.28 build.\n"
+                    L"sacred_re will not patch it; the game runs unmodified.",
+                    L"sacred_re", MB_OK | MB_ICONWARNING);
+        return;
+    }
+    if (re::ConfigInt("debug", "WaitForDebugger", 0)) {
+        re::Log("waiting up to 60 s for a debugger to attach");
+        for (int i = 0; i < 600 && !IsDebuggerPresent(); ++i) {
+            Sleep(100);
+        }
+        re::Log(IsDebuggerPresent() ? "debugger attached" : "no debugger, continuing");
+    }
+    re::InstallHooks();
+}
+
+} // namespace
+
+BOOL APIENTRY DllMain(HMODULE module, DWORD reason, LPVOID) {
+    if (DetourIsHelperProcess()) {
+        return TRUE;
+    }
+    if (reason == DLL_PROCESS_ATTACH) {
+        DisableThreadLibraryCalls(module);
+        DetourRestoreAfterWith();
+        Startup(module);
+    }
+    return TRUE;
+}