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, 0 insertions, 156 deletions

diff --git a/src/core/window_manager.h b/src/core/window_manager.h
deleted file mode 100644
index 2da999a..0000000
--- a/src/core/window_manager.h
+++ /dev/null
@@ -1,156 +0,0 @@
-#ifndef SRDWM_WINDOW_MANAGER_H
-#define SRDWM_WINDOW_MANAGER_H
-
-#include <vector>
-#include <algorithm> // Required for std::remove_if
-#include <memory> // Required for std::unique_ptr
-#include <map>
-#include <string>
-#include <functional>
-#include <set> // Required for std::set
-
-#include "../input/input_handler.h"
-#include "../layouts/layout_engine.h"
-#include "../platform/platform.h" // For Event type
-#include "../layouts/layout.h" // For Monitor type
-
-class SRDWindow; // Forward declaration
-class InputHandler; // Forward declaration
-class LuaManager; // Forward declaration
-
-// Workspace structure
-struct Workspace {
-    int id;
-    std::string name;
-    std::vector<SRDWindow*> windows;
-    std::string layout;
-    bool visible;
-    
-    Workspace(int id, const std::string& name = "") 
-        : id(id), name(name), layout("tiling"), visible(false) {}
-};
-
-class SRDWindowManager {
-public:
-    SRDWindowManager();
-    ~SRDWindowManager();
-
-    void run(); // Main loop
-
-    // SRDWindow management
-    void add_window(std::unique_ptr<SRDWindow> window);
-    void remove_window(SRDWindow* window);
-    void focus_window(SRDWindow* window);
-    SRDWindow* get_focused_window() const;
-    std::vector<SRDWindow*> get_windows() const;
-    void manage_windows(); // Added missing method
-    void focus_next_window();
-    void focus_previous_window();
-    
-    // SRDWindow operations
-    void close_window(SRDWindow* window);
-    void minimize_window(SRDWindow* window);
-    void maximize_window(SRDWindow* window);
-    void move_window(SRDWindow* window, int x, int y);
-    void resize_window(SRDWindow* window, int width, int height);
-    void toggle_window_floating(SRDWindow* window);
-    bool is_window_floating(SRDWindow* window) const;
-    
-    // Window dragging and resizing
-    void start_window_drag(SRDWindow* window, int start_x, int start_y);
-    void start_window_resize(SRDWindow* window, int start_x, int start_y, int edge);
-    void update_window_drag(int x, int y);
-    void update_window_resize(int x, int y);
-    void end_window_drag();
-    void end_window_resize();
-    bool is_dragging() const { return dragging_window_ != nullptr; }
-    bool is_resizing() const { return resizing_window_ != nullptr; }
-
-    // Workspace management
-    void add_workspace(const std::string& name = "");
-    void remove_workspace(int workspace_id);
-    void switch_to_workspace(int workspace_id);
-    void move_window_to_workspace(SRDWindow* window, int workspace_id);
-    int get_current_workspace() const;
-    std::vector<Workspace> get_workspaces() const;
-    Workspace* get_workspace(int workspace_id);
-    
-    // Layout management
-    void set_layout(int monitor_id, const std::string& layout_name);
-    std::string get_layout(int monitor_id) const;
-    void arrange_windows();
-    void tile_windows();
-    void arrange_windows_dynamic();
-
-    // Key binding system
-    void bind_key(const std::string& key_combination, std::function<void()> action);
-    void unbind_key(const std::string& key_combination);
-    void handle_key_press(int key_code, int modifiers);
-    void handle_key_release(int key_code, int modifiers);
-    
-    // Input event handling (called by InputHandler)
-    void handle_key_press(int key_code);
-    void handle_key_release(int key_code);
-    void handle_mouse_button_press(int button, int x, int y);
-    void handle_mouse_button_release(int button, int x, int y);
-    void handle_mouse_motion(int x, int y);
-    void handle_event(const Event& event); // Added missing method
-
-    // Integration
-    void set_layout_engine(LayoutEngine* engine);
-    void set_lua_manager(LuaManager* manager);
-    void set_platform(Platform* platform);
-
-private:
-    // Window tracking
-    std::vector<SRDWindow*> windows_; // Added missing member variable
-    SRDWindow* focused_window_ = nullptr;
-    std::set<SRDWindow*> floating_windows_; // Track floating windows
-    InputHandler* input_handler_ = nullptr;
-    LayoutEngine* layout_engine_ = nullptr;
-    LuaManager* lua_manager_ = nullptr;
-    Platform* platform_ = nullptr;
-
-    // Workspace management
-    std::vector<Workspace> workspaces_;
-    int current_workspace_ = 0;
-    int next_workspace_id_ = 1;
-    
-    // Window dragging and resizing state
-    SRDWindow* dragging_window_ = nullptr;
-    SRDWindow* resizing_window_ = nullptr;
-    int drag_start_x_ = 0;
-    int drag_start_y_ = 0;
-    int drag_start_window_x_ = 0;
-    int drag_start_window_y_ = 0;
-    int resize_start_x_ = 0;
-    int resize_start_y_ = 0;
-    int resize_start_width_ = 0;
-    int resize_start_height_ = 0;
-    int resize_edge_ = 0; // 0=none, 1=left, 2=right, 3=top, 4=bottom, 5=corner
-
-    // Key binding system
-    std::map<std::string, std::function<void()>> key_bindings_;
-    std::map<int, int> pressed_keys_; // key_code -> modifiers
-    
-    // Platform-specific data (placeholder)
-    void* platform_data_ = nullptr;
-    
-    // Monitor information
-    std::vector<Monitor> monitors_;
-    
-    // Helper methods
-    std::string key_code_to_string(int key_code, int modifiers) const;
-    void execute_key_binding(const std::string& key_combination);
-    void update_layout_for_window(SRDWindow* window);
-    void arrange_workspace_windows(int workspace_id);
-    void update_workspace_visibility();
-    
-    // Window interaction helpers
-    SRDWindow* find_window_at_position(int x, int y) const;
-    bool is_in_titlebar_area(SRDWindow* window, int x, int y) const;
-    bool is_in_resize_area(SRDWindow* window, int x, int y) const;
-    int get_resize_edge(SRDWindow* window, int x, int y) const;
-};
-
-#endif // SRDWM_WINDOW_MANAGER_H