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, 140 deletions

diff --git a/src/platform/windows_platform.h b/src/platform/windows_platform.h
deleted file mode 100644
index 70b7d54..0000000
--- a/src/platform/windows_platform.h
+++ /dev/null
@@ -1,140 +0,0 @@
-#ifndef SRDWM_WINDOWS_PLATFORM_H
-#define SRDWM_WINDOWS_PLATFORM_H
-
-#include "platform.h"
-#include <windows.h>
-#include <memory>
-#include <string>
-#include <map>
-
-class SRDWindowsPlatform : public Platform {
-public:
-    SRDWindowsPlatform();
-    ~SRDWindowsPlatform() override;
-
-    // Platform interface implementation
-    bool initialize() override;
-    void shutdown() override;
-    
-    bool poll_events(std::vector<Event>& events) override;
-    void process_event(const Event& event) override;
-    
-    std::unique_ptr<SRDWindow> create_window(const std::string& title, int x, int y, int width, int height) override;
-    void destroy_window(SRDWindow* window) override;
-    void set_window_position(SRDWindow* window, int x, int y) override;
-    void set_window_size(SRDWindow* window, int width, int height) override;
-    void set_window_title(SRDWindow* window, const std::string& title) override;
-    void focus_window(SRDWindow* window) override;
-    void minimize_window(SRDWindow* window) override;
-    void maximize_window(SRDWindow* window) override;
-    void close_window(SRDWindow* window) override;
-    
-    std::vector<Monitor> get_monitors() override;
-    Monitor get_primary_monitor() override;
-    
-    void grab_keyboard() override;
-    void ungrab_keyboard() override;
-    void grab_pointer() override;
-    void ungrab_pointer() override;
-    
-    // SRDWindow decorations (SRDWindows implementation)
-    void set_window_decorations(SRDWindow* window, bool enabled) override;
-    void set_window_border_color(SRDWindow* window, int r, int g, int b) override;
-    void set_window_border_width(SRDWindow* window, int width) override;
-    bool get_window_decorations(SRDWindow* window) const override;
-
-    // Windows-specific features
-    void enable_dwm_composition(bool enabled);
-    void set_dwm_window_attribute(HWND hwnd, DWORD attribute, DWORD value);
-    void set_dwm_window_thumbnail(HWND hwnd, HWND thumbnail_hwnd);
-    void set_dwm_window_peek(HWND hwnd, bool enabled);
-    
-    // Virtual Desktop support (Windows 10+)
-    void create_virtual_desktop();
-    void remove_virtual_desktop(int desktop_id);
-    void switch_to_virtual_desktop(int desktop_id);
-    int get_current_virtual_desktop() const;
-    std::vector<int> get_virtual_desktops() const;
-    void move_window_to_desktop(SRDWindow* window, int desktop_id);
-    
-    // Taskbar integration
-    void set_taskbar_visible(bool visible);
-    void set_taskbar_position(int position); // 0=bottom, 1=top, 2=left, 3=right
-    void set_taskbar_auto_hide(bool enabled);
-    void update_taskbar_preview(HWND hwnd, const std::string& title);
-    
-    // Aero effects
-    void enable_aero_effects(bool enabled);
-    void set_window_transparency(HWND hwnd, BYTE alpha);
-    void set_window_blur(HWND hwnd, bool enabled);
-    void set_window_shadow(HWND hwnd, bool enabled);
-    
-    // System tray integration
-    void add_system_tray_icon(const std::string& tooltip, HICON icon);
-    void remove_system_tray_icon();
-    void show_system_tray_menu(HMENU menu);
-
-    std::string get_platform_name() const override;
-    bool is_wayland() const override;
-    bool is_x11() const override;
-    bool is_windows() const override;
-    bool is_macos() const override;
-
-private:
-    bool initialized_;
-    HINSTANCE h_instance_;
-    std::map<HWND, SRDWindow*> window_map_;
-    std::vector<Monitor> monitors_;
-    
-    // Decoration state
-    bool decorations_enabled_;
-    int border_width_;
-    COLORREF border_color_;
-    COLORREF focused_border_color_;
-    
-    // Windows-specific state
-    bool dwm_enabled_;
-    bool aero_enabled_;
-    bool taskbar_visible_;
-    bool taskbar_auto_hide_;
-    int taskbar_position_;
-    int current_virtual_desktop_;
-    std::vector<int> virtual_desktops_;
-    NOTIFYICONDATA system_tray_icon_;
-    
-    // SRDWindow class registration
-    bool register_window_class();
-    void unregister_window_class();
-    
-    // SRDWindow procedure
-    static LRESULT CALLBACK window_proc(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam);
-    
-    // Event conversion
-    void convert_win32_message(UINT msg, WPARAM wparam, LPARAM lparam, std::vector<Event>& events);
-    
-    // Monitor enumeration
-    static BOOL CALLBACK enum_monitor_proc(HMONITOR hmonitor, HDC hdc_monitor, LPRECT lprc_monitor, LPARAM dw_data);
-    
-    // Utility methods
-    void update_monitors();
-    SRDWindow* find_window_by_hwnd(HWND hwnd);
-    
-    // Decoration methods
-    void apply_dwm_border_color(HWND hwnd, int r, int g, int b);
-    void remove_dwm_border_color(HWND hwnd);
-    
-    // Virtual Desktop methods
-    void initialize_virtual_desktops();
-    void cleanup_virtual_desktops();
-    
-    // DWM methods
-    bool initialize_dwm();
-    void cleanup_dwm();
-    
-    // Taskbar methods
-    void initialize_taskbar();
-    void update_taskbar();
-};
-
-#endif // SRDWM_WINDOWS_PLATFORM_H
-