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, 126 deletions

diff --git a/src/utils/logger.cc b/src/utils/logger.cc
deleted file mode 100644
index 92d26d9..0000000
--- a/src/utils/logger.cc
+++ /dev/null
@@ -1,126 +0,0 @@
-#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());
-}