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, 101 insertions, 0 deletions

diff --git a/legacy-cpp/src/config/config_manager.h b/legacy-cpp/src/config/config_manager.h
new file mode 100644
index 0000000..97f751e
--- /dev/null
+++ b/legacy-cpp/src/config/config_manager.h
@@ -0,0 +1,101 @@
+#ifndef SRDWM_CONFIG_MANAGER_H
+#define SRDWM_CONFIG_MANAGER_H
+
+#include <string>
+#include <memory>
+#include <map>
+#include <functional>
+#include <vector> // Added missing include
+
+// Forward declarations
+class WindowManager;
+
+// Configuration manager for srdwm
+class ConfigManager {
+public:
+    struct KeyBinding {
+        std::string key;
+        std::string command;
+        std::string description;
+    };
+
+    struct LayoutConfig {
+        std::string name;
+        std::string type; // "tiling", "dynamic", "floating"
+        std::map<std::string, std::string> properties;
+    };
+
+    struct ThemeConfig {
+        std::string name;
+        std::map<std::string, std::string> colors;
+        std::map<std::string, std::string> fonts;
+        std::map<std::string, int> dimensions;
+    };
+
+    ConfigManager();
+    ~ConfigManager();
+
+    // Configuration loading
+    bool load_config(const std::string& config_path);
+    bool reload_config();
+    
+    // Configuration access
+    std::string get_string(const std::string& key, const std::string& default_value = "") const;
+    int get_int(const std::string& key, int default_value = 0) const;
+    bool get_bool(const std::string& key, bool default_value = false) const;
+    double get_float(const std::string& key, double default_value = 0.0) const;
+    
+    // Key bindings
+    std::vector<KeyBinding> get_key_bindings() const;
+    bool add_key_binding(const std::string& key, const std::string& command, const std::string& description = "");
+    bool remove_key_binding(const std::string& key);
+    
+    // Layout configuration
+    std::vector<LayoutConfig> get_layout_configs() const;
+    LayoutConfig get_layout_config(const std::string& name) const;
+    
+    // Theme configuration
+    ThemeConfig get_theme_config() const;
+    bool set_theme(const std::string& theme_name);
+    
+    // Window rules
+    struct WindowRule {
+        std::string match_type; // "class", "title", "role"
+        std::string match_value;
+        std::map<std::string, std::string> properties;
+    };
+    
+    std::vector<WindowRule> get_window_rules() const;
+    bool add_window_rule(const WindowRule& rule);
+    
+    // Configuration validation
+    bool validate_config() const;
+    std::vector<std::string> get_validation_errors() const;
+
+private:
+    std::string config_path_;
+    std::map<std::string, std::string> string_values_;
+    std::map<std::string, int> int_values_;
+    std::map<std::string, bool> bool_values_;
+    std::map<std::string, double> float_values_;
+    
+    std::vector<KeyBinding> key_bindings_;
+    std::vector<LayoutConfig> layout_configs_;
+    std::vector<WindowRule> window_rules_;
+    ThemeConfig current_theme_;
+    
+    std::vector<std::string> validation_errors_;
+    
+    // Private methods
+    void parse_config_file(const std::string& content);
+    void setup_default_config();
+    bool validate_key_binding(const KeyBinding& binding) const;
+    bool validate_layout_config(const LayoutConfig& config) const;
+    bool validate_window_rule(const WindowRule& rule) const;
+    
+    // Lua integration (placeholder for future implementation)
+    bool execute_lua_config(const std::string& lua_code);
+};
+
+#endif // SRDWM_CONFIG_MANAGER_H
+