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, 38 insertions, 0 deletions

diff --git a/legacy-cpp/src/layouts/tiling_layout.cc b/legacy-cpp/src/layouts/tiling_layout.cc
new file mode 100644
index 0000000..440c95a
--- /dev/null
+++ b/legacy-cpp/src/layouts/tiling_layout.cc
@@ -0,0 +1,38 @@
+#include "tiling_layout.h"
+#include <iostream>
+
+TilingLayout::TilingLayout() {
+    // Constructor implementation
+}
+
+TilingLayout::~TilingLayout() {
+    // Destructor implementation
+}
+
+void TilingLayout::arrange_windows(const std::vector<SRDWindow*>& windows, const Monitor& monitor) {
+    std::cout << "TilingLayout::arrange_windows called for monitor:" << std::endl;
+    std::cout << "  Position: (" << monitor.x << ", " << monitor.y << "), Dimensions: (" << monitor.width << ", " << monitor.height << ")" << std::endl;
+    std::cout << "  Number of windows: " << windows.size() << std::endl;
+
+    // Basic placeholder tiling logic (e.g., splitting the screen vertically)
+    if (!windows.empty()) {
+        int window_width = monitor.width / windows.size();
+        int current_x = monitor.x;
+
+        for (size_t i = 0; i < windows.size(); ++i) {
+            SRDWindow* window = windows[i];
+            // In a real implementation, you would calculate the desired
+            // position and size for the window based on the tiling algorithm
+            // and then call a method on the window object (which would
+            // internally use the platform backend) to apply these changes.
+            std::cout << "    SRDWindow " << window->getId() << ": Placeholder position (" << current_x << ", " << monitor.y << "), size (" << window_width << ", " << monitor.height << ")" << std::endl;
+
+            // Update the window's properties in the SRDWindow object
+            window->setPosition(current_x, monitor.y);
+            window->setDimensions(current_x, monitor.y, window_width, monitor.height);
+
+
+            current_x += window_width;
+        }
+    }
+}