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, 187 deletions

diff --git a/tests/test_smart_placement.cc b/tests/test_smart_placement.cc
deleted file mode 100644
index 6690984..0000000
--- a/tests/test_smart_placement.cc
+++ /dev/null
@@ -1,187 +0,0 @@
-#include <gtest/gtest.h>
-#include "../src/layouts/smart_placement.h"
-#include "../src/core/window.h"
-#include "../src/layouts/layout.h"
-
-class SmartPlacementTest : public ::testing::Test {
-protected:
-    void SetUp() override {
-        // Create test monitor
-        monitor.id = 1;
-        monitor.name = "Test Monitor";
-        monitor.x = 0;
-        monitor.y = 0;
-        monitor.width = 1920;
-        monitor.height = 1080;
-        monitor.refresh_rate = 60;
-        
-        // Create test windows
-        for (int i = 0; i < 5; ++i) {
-            auto window = std::make_unique<Window>();
-            window->setId(i + 1);
-            window->setTitle("Test Window " + std::to_string(i + 1));
-            window->setPosition(100 + i * 50, 100 + i * 50);
-            window->setSize(400, 300);
-            existing_windows.push_back(std::move(window));
-        }
-    }
-    
-    Monitor monitor;
-    std::vector<std::unique_ptr<Window>> existing_windows;
-};
-
-TEST_F(SmartPlacementTest, GridPlacement) {
-    auto window = std::make_unique<Window>();
-    window->setId(100);
-    window->setTitle("Grid Test Window");
-    window->setSize(400, 300);
-    
-    auto result = SmartPlacement::place_in_grid(window.get(), monitor, existing_windows);
-    
-    EXPECT_TRUE(result.success);
-    EXPECT_GE(result.x, monitor.x);
-    EXPECT_LE(result.x + window->getWidth(), monitor.x + monitor.width);
-    EXPECT_GE(result.y, monitor.y);
-    EXPECT_LE(result.y + window->getHeight(), monitor.y + monitor.height);
-}
-
-TEST_F(SmartPlacementTest, CascadePlacement) {
-    auto window = std::make_unique<Window>();
-    window->setId(101);
-    window->setTitle("Cascade Test Window");
-    window->setSize(400, 300);
-    
-    auto result = SmartPlacement::cascade_place(window.get(), monitor, existing_windows);
-    
-    EXPECT_TRUE(result.success);
-    EXPECT_GE(result.x, monitor.x);
-    EXPECT_LE(result.x + window->getWidth(), monitor.x + monitor.width);
-    EXPECT_GE(result.y, monitor.y);
-    EXPECT_LE(result.y + window->getHeight(), monitor.y + monitor.height);
-}
-
-TEST_F(SmartPlacementTest, SnapToEdge) {
-    auto window = std::make_unique<Window>();
-    window->setId(102);
-    window->setTitle("Snap Test Window");
-    window->setSize(400, 300);
-    
-    auto result = SmartPlacement::snap_to_edge(window.get(), monitor, existing_windows);
-    
-    EXPECT_TRUE(result.success);
-    EXPECT_GE(result.x, monitor.x);
-    EXPECT_LE(result.x + window->getWidth(), monitor.x + monitor.width);
-    EXPECT_GE(result.y, monitor.y);
-    EXPECT_LE(result.y + window->getHeight(), monitor.y + monitor.height);
-}
-
-TEST_F(SmartPlacementTest, SmartTile) {
-    auto window = std::make_unique<Window>();
-    window->setId(103);
-    window->setTitle("Smart Tile Test Window");
-    window->setSize(400, 300);
-    
-    auto result = SmartPlacement::smart_tile(window.get(), monitor, existing_windows);
-    
-    EXPECT_TRUE(result.success);
-    EXPECT_GE(result.x, monitor.x);
-    EXPECT_LE(result.x + window->getWidth(), monitor.x + monitor.width);
-    EXPECT_GE(result.y, monitor.y);
-    EXPECT_LE(result.y + window->getHeight(), monitor.y + monitor.height);
-}
-
-TEST_F(SmartPlacementTest, OverlapDetection) {
-    auto window1 = std::make_unique<Window>();
-    window1->setId(200);
-    window1->setPosition(100, 100);
-    window1->setSize(400, 300);
-    
-    auto window2 = std::make_unique<Window>();
-    window2->setId(201);
-    window2->setPosition(200, 200);
-    window2->setSize(400, 300);
-    
-    EXPECT_TRUE(SmartPlacement::windows_overlap(window1.get(), window2.get()));
-    
-    auto window3 = std::make_unique<Window>();
-    window3->setId(202);
-    window3->setPosition(600, 600);
-    window3->setSize(400, 300);
-    
-    EXPECT_FALSE(SmartPlacement::windows_overlap(window1.get(), window3.get()));
-}
-
-TEST_F(SmartPlacementTest, OptimalGridSize) {
-    auto grid_size = SmartPlacement::calculate_optimal_grid_size(4, monitor);
-    EXPECT_GT(grid_size.first, 0);
-    EXPECT_GT(grid_size.second, 0);
-    EXPECT_LE(grid_size.first * grid_size.second, 6); // Should fit 4 windows with some margin
-}
-
-TEST_F(SmartPlacementTest, FreeSpaceFinding) {
-    auto free_spaces = SmartPlacement::find_free_spaces(monitor, existing_windows);
-    EXPECT_FALSE(free_spaces.empty());
-    
-    for (const auto& space : free_spaces) {
-        EXPECT_GT(space.width, 0);
-        EXPECT_GT(space.height, 0);
-        EXPECT_GE(space.x, monitor.x);
-        EXPECT_GE(space.y, monitor.y);
-        EXPECT_LE(space.x + space.width, monitor.x + monitor.width);
-        EXPECT_LE(space.y + space.height, monitor.y + monitor.height);
-    }
-}
-
-TEST_F(SmartPlacementTest, PositionValidation) {
-    auto window = std::make_unique<Window>();
-    window->setId(300);
-    window->setSize(400, 300);
-    
-    // Valid position
-    EXPECT_TRUE(SmartPlacement::is_position_valid(100, 100, window.get(), monitor, existing_windows));
-    
-    // Invalid position (outside monitor)
-    EXPECT_FALSE(SmartPlacement::is_position_valid(-100, -100, window.get(), monitor, existing_windows));
-    EXPECT_FALSE(SmartPlacement::is_position_valid(2000, 2000, window.get(), monitor, existing_windows));
-}
-
-TEST_F(SmartPlacementTest, GridPositionCalculation) {
-    auto grid_size = std::make_pair(2, 2);
-    auto cell_size = std::make_pair(monitor.width / 2, monitor.height / 2);
-    
-    auto pos = SmartPlacement::calculate_grid_position(0, 0, grid_size, cell_size, monitor);
-    EXPECT_EQ(pos.first, monitor.x);
-    EXPECT_EQ(pos.second, monitor.y);
-    
-    pos = SmartPlacement::calculate_grid_position(1, 1, grid_size, cell_size, monitor);
-    EXPECT_EQ(pos.first, monitor.x + cell_size.first);
-    EXPECT_EQ(pos.second, monitor.y + cell_size.second);
-}
-
-TEST_F(SmartPlacementTest, OverlapScoreCalculation) {
-    auto window1 = std::make_unique<Window>();
-    window1->setId(400);
-    window1->setPosition(100, 100);
-    window1->setSize(400, 300);
-    
-    auto window2 = std::make_unique<Window>();
-    window2->setId(401);
-    window2->setPosition(200, 200);
-    window2->setSize(400, 300);
-    
-    auto score = SmartPlacement::calculate_overlap_score(window1.get(), window2.get());
-    EXPECT_GT(score, 0);
-    
-    auto window3 = std::make_unique<Window>();
-    window3->setId(402);
-    window3->setPosition(600, 600);
-    window3->setSize(400, 300);
-    
-    score = SmartPlacement::calculate_overlap_score(window1.get(), window3.get());
-    EXPECT_EQ(score, 0);
-}
-
-int main(int argc, char **argv) {
-    ::testing::InitGoogleTest(&argc, argv);
-    return RUN_ALL_TESTS();
-}