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.

1 files changed, 49 insertions, 0 deletions

diff --git a/legacy-cpp/src/core/window.h b/legacy-cpp/src/core/window.h
new file mode 100644
index 0000000..6d7405a
--- /dev/null
+++ b/legacy-cpp/src/core/window.h
@@ -0,0 +1,49 @@
+#ifndef WINDOW_H
+#define WINDOW_H
+
+#include <string>
+
+class SRDWindow {
+public:
+    // Constructor
+    SRDWindow(int id, const std::string& title);
+
+    // Getters
+    int getId() const;
+    const std::string& getTitle() const;
+    int getX() const;
+    int getY() const;
+    int getWidth() const;
+    int getHeight() const;
+    bool isDecorated() const;
+
+    // Setters
+    void setTitle(const std::string& title);
+    void setPosition(int x, int y);
+    void setSize(int width, int height);
+    void setGeometry(int x, int y, int width, int height);
+    void setDimensions(int x, int y, int width, int height);
+    void setDecorated(bool decorated);
+    void setId(int id);
+
+    // Window management methods
+    void map();
+    void unmap();
+    void focus();
+    void close();
+
+    // Comparison operators for use in containers
+    bool operator<(const SRDWindow& other) const { return id_ < other.id_; }
+    bool operator==(const SRDWindow& other) const { return id_ == other.id_; }
+
+private:
+    int id_;
+    std::string title_;
+    int x_;
+    int y_;
+    int width_;
+    int height_;
+    bool decorated_;
+};
+
+#endif // WINDOW_H