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>

README.md

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+# sacred_re
+
+An incremental reimplementation of **Sacred Gold 2.28** (`sacred.exe`, 2006).
+
+`sacred_re.dll` is injected into the original game at startup and replaces game
+functions with rewritten C++ one by one. Everything not yet rewritten keeps
+running as original machine code, so the game stays playable at every step and
+each rewrite can be tested in-game immediately. Once enough is rewritten, the
+original executable can be dropped.
+
+No game assets or original code are included; you need your own installed copy
+of Sacred Gold.
+
+## Supported build
+
+Only this executable is supported (all hook addresses are specific to it):
+
+| | |
+|---|---|
+| File | `sacred.exe`, 12,103,680 bytes |
+| SHA-256 | `fe774c6f985b02c9ce03103c2e55e5d853258c0cc3c737ccd211219c74460cb9` |
+| PE timestamp | `0x451BBE74` (2006-09-28) |
+
+The DLL checks the timestamp and image size at startup and leaves any other
+build unpatched.
+
+## Building
+
+Requirements: Visual Studio 2022 Build Tools ("Desktop development with C++",
+MSVC x86 + Windows SDK), CMake ≥ 3.24, Ninja, git (Detours is fetched at
+configure time).
+
+```powershell
+.\build.ps1               # x86-debug   -> build\x86-debug\
+.\build.ps1 x86-release   # x86-release -> build\x86-release\
+```
+
+Everything is 32-bit x86: the code runs inside the 32-bit game process. In an
+IDE (CLion, VS Code), select an MSVC toolchain with **x86** architecture and use
+the CMake presets.
+
+## Running
+
+```powershell
+build\x86-debug\sacred_re.exe --game-dir "D:\Gaming\Sacred Gold"   # first run; remembered in sacred_re.ini
+build\x86-debug\sacred_re.exe log                                  # later runs; extra args go to the game
+```
+
+`sacred_re.log` (next to the DLL) records what was hooked plus every message the
+game sends to its internal logger, even when the game's own logging is off.
+
+Hooks can be switched off individually in `sacred_re.ini` (next to the DLL)
+to compare a rewrite against the original:
+
+```ini
+[hooks]
+CmdLineHasFlag=0
+```
+
+## Layout
+
+```
+src/re/         hook framework, injection-side startup, logging, config
+src/launcher/   sacred_re.exe — starts sacred.exe with the DLL injected
+src/game/       rewritten game code and original-layout structs, by subsystem
+src/mods/       behaviour changes on top of the original (e.g. borderless.cpp)
+docs/           reverse-engineering notes; function-map.md tracks progress
+```
+
+## Adding a rewritten function
+
+```cpp
+namespace game {
+bool __cdecl CmdLineHasFlag(const char* cmdline, const char* flag, bool quiet);
+RE_HOOK(0x00813140, CmdLineHasFlag);   // also defines CmdLineHasFlag_original
+bool __cdecl CmdLineHasFlag(const char* cmdline, const char* flag, bool quiet) { ... }
+}
+```
+
+The signature and calling convention must match the original exactly. Add the
+file to `CMakeLists.txt` and a row to `docs/function-map.md`.
+
+## Portability rules (for an eventual 64-bit build)
+
+The game is 32-bit and must stay so while we hook into it, but new code should
+not make that permanent:
+
+- use fixed-width types (`uint32_t`, not `long`/`DWORD`) for anything with a
+  fixed layout;
+- never store pointers in, or cast pointers to, 32-bit integers;
+- keep file and network formats behind explicit serialization code instead of
+  `fwrite`-ing structs.