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.

2 files changed, 218 insertions, 0 deletions

diff --git a/legacy-cpp/src/utils/logger.cc b/legacy-cpp/src/utils/logger.cc
new file mode 100644
index 0000000..92d26d9
--- /dev/null
+++ b/legacy-cpp/src/utils/logger.cc
@@ -0,0 +1,126 @@
+#include "logger.h"
+#include <iostream>
+#include <fstream>
+#include <chrono>
+#include <iomanip>
+#include <ctime>
+
+// Global logger instance
+Logger g_logger;
+
+Logger::Logger() 
+    : current_level(LogLevel::INFO)
+    , console_enabled(true)
+    , file_enabled(false) {
+}
+
+Logger::~Logger() {
+    if (file_stream) {
+        file_stream->flush();
+    }
+}
+
+void Logger::set_level(LogLevel level) {
+    current_level = level;
+}
+
+void Logger::debug(const std::string& message) {
+    log(LogLevel::DEBUG, message);
+}
+
+void Logger::info(const std::string& message) {
+    log(LogLevel::INFO, message);
+}
+
+void Logger::warning(const std::string& message) {
+    log(LogLevel::WARNING, message);
+}
+
+void Logger::error(const std::string& message) {
+    log(LogLevel::ERROR, message);
+}
+
+void Logger::fatal(const std::string& message) {
+    log(LogLevel::FATAL, message);
+}
+
+void Logger::log(LogLevel level, const std::string& message) {
+    if (level >= current_level) {
+        write_log(level, message);
+    }
+}
+
+void Logger::set_output_file(const std::string& filename) {
+    output_filename = filename;
+    if (file_enabled && !filename.empty()) {
+        file_stream = std::make_unique<std::ofstream>(filename, std::ios::app);
+        if (!file_stream->good()) {
+            std::cerr << "Failed to open log file: " << filename << std::endl;
+            file_stream.reset();
+        }
+    }
+}
+
+void Logger::enable_console(bool enable) {
+    console_enabled = enable;
+}
+
+void Logger::enable_file(bool enable) {
+    file_enabled = enable;
+    if (enable && !output_filename.empty()) {
+        set_output_file(output_filename);
+    } else if (!enable) {
+        file_stream.reset();
+    }
+}
+
+std::string Logger::level_to_string(LogLevel level) {
+    switch (level) {
+        case LogLevel::DEBUG:   return "DEBUG";
+        case LogLevel::INFO:    return "INFO";
+        case LogLevel::WARNING: return "WARNING";
+        case LogLevel::ERROR:   return "ERROR";
+        case LogLevel::FATAL:   return "FATAL";
+        default:                return "UNKNOWN";
+    }
+}
+
+std::string Logger::get_timestamp() {
+    auto now = std::chrono::system_clock::now();
+    auto time_t = std::chrono::system_clock::to_time_t(now);
+    auto ms = std::chrono::duration_cast<std::chrono::milliseconds>(
+        now.time_since_epoch()) % 1000;
+    
+    std::stringstream ss;
+    ss << std::put_time(std::localtime(&time_t), "%Y-%m-%d %H:%M:%S");
+    ss << '.' << std::setfill('0') << std::setw(3) << ms.count();
+    return ss.str();
+}
+
+void Logger::write_log(LogLevel level, const std::string& message) {
+    std::string timestamp = get_timestamp();
+    std::string level_str = level_to_string(level);
+    std::string log_entry = "[" + timestamp + "] [" + level_str + "] " + message + "\n";
+    
+    if (console_enabled) {
+        if (level == LogLevel::ERROR || level == LogLevel::FATAL) {
+            std::cerr << log_entry;
+        } else {
+            std::cout << log_entry;
+        }
+    }
+    
+    if (file_enabled && file_stream && file_stream->good()) {
+        *file_stream << log_entry;
+        file_stream->flush();
+    }
+}
+
+// LogStream implementation
+LogStream::LogStream(Logger& logger, LogLevel level) 
+    : logger(logger), level(level) {
+}
+
+LogStream::~LogStream() {
+    logger.log(level, stream.str());
+}
diff --git a/legacy-cpp/src/utils/logger.h b/legacy-cpp/src/utils/logger.h
new file mode 100644
index 0000000..2896c7e
--- /dev/null
+++ b/legacy-cpp/src/utils/logger.h
@@ -0,0 +1,92 @@
+#ifndef SRDWM_LOGGER_H
+#define SRDWM_LOGGER_H
+
+#include <string>
+#include <sstream>
+#include <memory>
+
+// Log levels
+enum class LogLevel {
+    DEBUG,
+    INFO,
+    WARNING,
+    ERROR,
+    FATAL
+};
+
+// Logger class
+class Logger {
+public:
+    Logger();
+    ~Logger();
+    
+    // Set log level
+    void set_level(LogLevel level);
+    
+    // Logging methods
+    void debug(const std::string& message);
+    void info(const std::string& message);
+    void warning(const std::string& message);
+    void error(const std::string& message);
+    void fatal(const std::string& message);
+    
+    // Log with level
+    void log(LogLevel level, const std::string& message);
+    
+    // Set output file
+    void set_output_file(const std::string& filename);
+    
+    // Enable/disable console output
+    void enable_console(bool enable);
+    
+    // Enable/disable file output
+    void enable_file(bool enable);
+
+private:
+    LogLevel current_level;
+    bool console_enabled;
+    bool file_enabled;
+    std::string output_filename;
+    std::unique_ptr<std::ostream> file_stream;
+    
+    std::string level_to_string(LogLevel level);
+    std::string get_timestamp();
+    void write_log(LogLevel level, const std::string& message);
+};
+
+// Global logger instance
+extern Logger g_logger;
+
+// Convenience macros
+#define LOG_DEBUG(msg) g_logger.debug(msg)
+#define LOG_INFO(msg) g_logger.info(msg)
+#define LOG_WARNING(msg) g_logger.warning(msg)
+#define LOG_ERROR(msg) g_logger.error(msg)
+#define LOG_FATAL(msg) g_logger.fatal(msg)
+
+// Stream-based logging
+class LogStream {
+public:
+    LogStream(Logger& logger, LogLevel level);
+    ~LogStream();
+    
+    template<typename T>
+    LogStream& operator<<(const T& value) {
+        stream << value;
+        return *this;
+    }
+
+private:
+    Logger& logger;
+    LogLevel level;
+    std::ostringstream stream;
+};
+
+// Stream logging macros
+#define LOG_STREAM_DEBUG LogStream(g_logger, LogLevel::DEBUG)
+#define LOG_STREAM_INFO LogStream(g_logger, LogLevel::INFO)
+#define LOG_STREAM_WARNING LogStream(g_logger, LogLevel::WARNING)
+#define LOG_STREAM_ERROR LogStream(g_logger, LogLevel::ERROR)
+#define LOG_STREAM_FATAL LogStream(g_logger, LogLevel::FATAL)
+
+#endif // SRDWM_LOGGER_H