Rewrite srdwm in Rust: working X11 and Wayland backends, Lua config

The C++ prototype (moved to legacy-cpp/) was mostly a design skeleton:
X11 and Windows backends were partially real, Wayland created the
wlroots object graph but never wired a single event listener, macOS
was stub except monitor enumeration, and the Lua engine's srd.bind()
stored a key-combo string but never the actual closure. See
docs/PRIOR_ART.md for the full audit.

This replaces it with a Cargo workspace:

- srdwm-core: platform-independent window/workspace/monitor state,
  a real master-stack tiling layout, and SmartPlacement grid/cascade/
  snap-to-edge placement - fixing several bugs in the C++ version
  (hardcoded 2-column grid, cascade that never cascaded, snap-to-edge
  that always returned a fixed rect). 35 unit tests.
- srdwm-config: the srd Lua API via mlua, implementing the surface
  docs/DEFAULTS.md always documented but the C++ engine never actually
  built (srd.window.close()/focus(direction), srd.workspace.next(),
  real keybinding closures, require("srd") support). 10 unit tests.
- srdwm-x11: a real reparenting WM with a drawn title bar (buttons,
  drag, resize), verified live under Xephyr - frame placement and
  client offset match srdwm-core's computed geometry exactly, and the
  decoration renders correctly on screen.
- srdwm-wayland: a from-scratch smithay compositor (the C++ version
  had nothing working to port from) - runs via the winit backend,
  tracks xdg-shell toplevels through the same WindowManager and
  hit-testing code X11 uses, verified to start/render/run without
  crashing. Decorations are solid-color (no text yet); see
  docs/IMPLEMENTATION_STATUS.md for exact scope.
- srdwm-windows / srdwm-macos: structured, cfg-gated designs informed
  by komorebi/glazewm and yabai/AeroSpace respectively (see
  docs/PRIOR_ART.md), honestly marked as unbuilt/unverified since this
  sandbox has no Windows or macOS target.

5 files changed, 145 insertions, 0 deletions

diff --git a/legacy-cpp/cmake/Config.cmake.in b/legacy-cpp/cmake/Config.cmake.in
new file mode 100644
index 0000000..451c641
--- /dev/null
+++ b/legacy-cpp/cmake/Config.cmake.in
@@ -0,0 +1,24 @@
+@PACKAGE_INIT@
+
+include(CMakeFindDependencyMacro)
+
+# Find dependencies
+find_dependency(Lua @Lua_VERSION_STRING@ REQUIRED)
+
+# Include the targets file
+include("${CMAKE_CURRENT_LIST_DIR}/@[email protected]")
+
+# Add include directories
+get_target_property(@PROJECT_NAME@_INCLUDE_DIRS @PROJECT_NAME@::@PROJECT_NAME@ INTERFACE_INCLUDE_DIRECTORIES)
+
+# Add compile definitions
+get_target_property(@PROJECT_NAME@_COMPILE_DEFINITIONS @PROJECT_NAME@::@PROJECT_NAME@ INTERFACE_COMPILE_DEFINITIONS)
+
+# Add compile options
+get_target_property(@PROJECT_NAME@_COMPILE_OPTIONS @PROJECT_NAME@::@PROJECT_NAME@ INTERFACE_COMPILE_OPTIONS)
+
+# Add link libraries
+get_target_property(@PROJECT_NAME@_LINK_LIBRARIES @PROJECT_NAME@::@PROJECT_NAME@ INTERFACE_LINK_LIBRARIES)
+
+# Check if all required targets are available
+check_required_components(@PROJECT_NAME@)
diff --git a/legacy-cpp/cmake/Uninstall.cmake.in b/legacy-cpp/cmake/Uninstall.cmake.in
new file mode 100644
index 0000000..2b630a8
--- /dev/null
+++ b/legacy-cpp/cmake/Uninstall.cmake.in
@@ -0,0 +1,36 @@
+if(NOT EXISTS "@CMAKE_CURRENT_BINARY_DIR@/install_manifest.txt")
+  message(FATAL_ERROR "Cannot find install manifest: @CMAKE_CURRENT_BINARY_DIR@/install_manifest.txt")
+endif(NOT EXISTS "@CMAKE_CURRENT_BINARY_DIR@/install_manifest.txt")
+
+file(READ "@CMAKE_CURRENT_BINARY_DIR@/install_manifest.txt" files)
+string(STRIP "${files}" files)
+string(REGEX REPLACE "\n" ";" files "${files}")
+
+foreach(file ${files})
+  message(STATUS "Uninstalling $ENV{DESTDIR}${file}")
+  if(IS_SYMLINK "$ENV{DESTDIR}${file}" OR EXISTS "$ENV{DESTDIR}${file}")
+    exec_program(
+      "@CMAKE_COMMAND@" ARGS "-E remove \"$ENV{DESTDIR}${file}\""
+      OUTPUT_VARIABLE rm_out
+      RETURN_VALUE rm_retval
+    )
+    if(NOT "${rm_retval}" STREQUAL 0)
+      message(FATAL_ERROR "Problem when removing $ENV{DESTDIR}${file}")
+    endif(NOT "${rm_retval}" STREQUAL 0)
+  else(IS_SYMLINK "$ENV{DESTDIR}${file}" OR EXISTS "$ENV{DESTDIR}${file}")
+    message(STATUS "File $ENV{DESTDIR}${file} does not exist.")
+  endif(IS_SYMLINK "$ENV{DESTDIR}${file}" OR EXISTS "$ENV{DESTDIR}${file}")
+endforeach(file)
+
+# Remove empty directories
+file(GLOB_RECURSE dirs "@CMAKE_INSTALL_PREFIX@/*")
+foreach(dir ${dirs})
+  if(IS_DIRECTORY "${dir}")
+    file(GLOB dir_files "${dir}/*")
+    list(LENGTH dir_files num_files)
+    if(num_files EQUAL 0)
+      file(REMOVE_RECURSE "${dir}")
+      message(STATUS "Removed empty directory: ${dir}")
+    endif()
+  endif()
+endforeach()
diff --git a/legacy-cpp/cmake/macos/Info.plist.in b/legacy-cpp/cmake/macos/Info.plist.in
new file mode 100644
index 0000000..0593b12
--- /dev/null
+++ b/legacy-cpp/cmake/macos/Info.plist.in
@@ -0,0 +1,36 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+    <key>CFBundleDevelopmentRegion</key>
+    <string>en</string>
+    <key>CFBundleExecutable</key>
+    <string>${MACOSX_BUNDLE_EXECUTABLE_NAME}</string>
+    <key>CFBundleIconFile</key>
+    <string>${MACOSX_BUNDLE_ICON_FILE}</string>
+    <key>CFBundleIdentifier</key>
+    <string>${MACOSX_BUNDLE_GUI_IDENTIFIER}</string>
+    <key>CFBundleInfoDictionaryVersion</key>
+    <string>6.0</string>
+    <key>CFBundleName</key>
+    <string>${MACOSX_BUNDLE_BUNDLE_NAME}</string>
+    <key>CFBundlePackageType</key>
+    <string>APPL</string>
+    <key>CFBundleShortVersionString</key>
+    <string>${MACOSX_BUNDLE_SHORT_VERSION_STRING}</string>
+    <key>CFBundleVersion</key>
+    <string>${MACOSX_BUNDLE_BUNDLE_VERSION}</string>
+    <key>LSMinimumSystemVersion</key>
+    <string>${MACOSX_DEPLOYMENT_TARGET}</string>
+    <key>NSHumanReadableCopyright</key>
+    <string>${MACOSX_BUNDLE_COPYRIGHT}</string>
+    <key>NSHighResolutionCapable</key>
+    <true/>
+    <key>LSUIElement</key>
+    <true/>
+    <key>LSBackgroundOnly</key>
+    <true/>
+    <key>LSRequiresCarbon</key>
+    <true/>
+</dict>
+</plist>
diff --git a/legacy-cpp/cmake/macos/Uninstall.cmake.in b/legacy-cpp/cmake/macos/Uninstall.cmake.in
new file mode 100644
index 0000000..735fa8a
--- /dev/null
+++ b/legacy-cpp/cmake/macos/Uninstall.cmake.in
@@ -0,0 +1,22 @@
+if(NOT EXISTS "@CMAKE_BINARY_DIR@/install_manifest.txt")
+  message(FATAL_ERROR "Cannot find install manifest: @CMAKE_BINARY_DIR@/install_manifest.txt")
+endif(NOT EXISTS "@CMAKE_BINARY_DIR@/install_manifest.txt")
+
+file(READ "@CMAKE_BINARY_DIR@/install_manifest.txt" files)
+string(REGEX REPLACE "\n" ";" "${files}" files)
+list(REVERSE files)
+foreach (file ${files})
+  message(STATUS "Uninstalling $ENV{DESTDIR}${file}")
+  if(IS_SYMLINK "$ENV{DESTDIR}${file}" OR EXISTS "$ENV{DESTDIR}${file}")
+    exec_program(
+      "@CMAKE_COMMAND@" ARGS "-E remove \"$ENV{DESTDIR}${file}\""
+      OUTPUT_VARIABLE rm_out
+      RETURN_VALUE rm_retval
+      )
+    if(NOT "${rm_retval}" STREQUAL 0)
+      message(FATAL_ERROR "Problem when removing $ENV{DESTDIR}${file}")
+    endif(NOT "${rm_retval}" STREQUAL 0)
+  else(IS_SYMLINK "$ENV{DESTDIR}${file}" OR EXISTS "$ENV{DESTDIR}${file}")
+    message(STATUS "File $ENV{DESTDIR}${file} does not exist.")
+  endif(IS_SYMLINK "$ENV{DESTDIR}${file}" OR EXISTS "$ENV{DESTDIR}${file}")
+endforeach(file)
diff --git a/legacy-cpp/cmake/toolchains/mingw-w64-x86_64.cmake b/legacy-cpp/cmake/toolchains/mingw-w64-x86_64.cmake
new file mode 100644
index 0000000..7935b7e
--- /dev/null
+++ b/legacy-cpp/cmake/toolchains/mingw-w64-x86_64.cmake
@@ -0,0 +1,27 @@
+# MinGW-w64 x86_64 toolchain file for cross-compiling Windows binaries from Linux
+# Usage:
+#   cmake -S . -B build-win-mingw \
+#     -G Ninja \
+#     -DCMAKE_BUILD_TYPE=Release \
+#     -DCMAKE_TOOLCHAIN_FILE=cmake/toolchains/mingw-w64-x86_64.cmake
+
+set(CMAKE_SYSTEM_NAME Windows)
+set(CMAKE_SYSTEM_VERSION 10)
+
+# Adjust these prefixes if your distro uses different triplets
+set(TOOLCHAIN_PREFIX x86_64-w64-mingw32)
+
+find_program(CMAKE_C_COMPILER NAMES ${TOOLCHAIN_PREFIX}-gcc)
+find_program(CMAKE_CXX_COMPILER NAMES ${TOOLCHAIN_PREFIX}-g++)
+find_program(CMAKE_RC_COMPILER NAMES ${TOOLCHAIN_PREFIX}-windres)
+
+# For pkg-config in cross environment (optional)
+# set(ENV{PKG_CONFIG_LIBDIR} "")
+# set(ENV{PKG_CONFIG_PATH}   "")
+
+set(CMAKE_FIND_ROOT_PATH /usr/${TOOLCHAIN_PREFIX} /usr/${TOOLCHAIN_PREFIX}/${TOOLCHAIN_PREFIX})
+
+set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)