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, 127 deletions

diff --git a/config/srd/test_decorations.lua b/config/srd/test_decorations.lua
deleted file mode 100644
index 2b49d0a..0000000
--- a/config/srd/test_decorations.lua
+++ /dev/null
@@ -1,127 +0,0 @@
-- Test configuration for decoration and window state controls
-- This file demonstrates the cross-platform decoration and tiling/floating functionality
-
-print("Loading decoration and window state test configuration...")
-
-- Global decoration settings
-srd.set("general.decorations_enabled", true)
-srd.set("general.border_width", 3)
-srd.set("general.border_color", "#2e3440")
-
-- Keybindings for decoration and window state controls
-srd.bind("Mod4+d", function()
-    - Toggle decorations for focused window
-    local window = srd.window.focused()
-    if window then
-        local current = srd.window.get_decorations(window.id)
-        srd.window.set_decorations(window.id, not current)
-        print("Toggled decorations for window " .. window.id)
-    end
-end)
-
-srd.bind("Mod4+b", function()
-    - Toggle border color for focused window
-    local window = srd.window.focused()
-    if window then
-        srd.window.set_border_color(window.id, 255, 0, 0) - Red border
-        print("Set red border for window " .. window.id)
-    end
-end)
-
-srd.bind("Mod4+n", function()
-    - Toggle border color back to normal
-    local window = srd.window.focused()
-    if window then
-        srd.window.set_border_color(window.id, 46, 52, 64) - Default color
-        print("Reset border color for window " .. window.id)
-    end
-end)
-
-srd.bind("Mod4+w", function()
-    - Toggle border width
-    local window = srd.window.focused()
-    if window then
-        srd.window.set_border_width(window.id, 8) - Thick border
-        print("Set thick border for window " .. window.id)
-    end
-end)
-
-srd.bind("Mod4+s", function()
-    - Reset border width
-    local window = srd.window.focused()
-    if window then
-        srd.window.set_border_width(window.id, 3) - Normal border
-        print("Reset border width for window " .. window.id)
-    end
-end)
-
-- Window state controls
-srd.bind("Mod4+f", function()
-    - Toggle floating state for focused window
-    local window = srd.window.focused()
-    if window then
-        srd.window.toggle_floating(window.id)
-        local floating = srd.window.is_floating(window.id)
-        print("Window " .. window.id .. " floating: " .. tostring(floating))
-    end
-end)
-
-srd.bind("Mod4+t", function()
-    - Set window to tiling mode
-    local window = srd.window.focused()
-    if window then
-        srd.window.set_floating(window.id, false)
-        print("Set window " .. window.id .. " to tiling mode")
-    end
-end)
-
-srd.bind("Mod4+l", function()
-    - Set window to floating mode
-    local window = srd.window.focused()
-    if window then
-        srd.window.set_floating(window.id, true)
-        print("Set window " .. window.id .. " to floating mode")
-    end
-end)
-
-- Layout switching with decoration awareness
-srd.bind("Mod4+1", function()
-    srd.layout.set("tiling")
-    print("Switched to tiling layout")
-end)
-
-srd.bind("Mod4+2", function()
-    srd.layout.set("dynamic")
-    print("Switched to dynamic layout")
-end)
-
-srd.bind("Mod4+3", function()
-    srd.layout.set("floating")
-    print("Switched to floating layout")
-end)
-
-- Test function to apply decorations to all windows
-function apply_test_decorations()
-    print("Applying test decorations to all windows...")
-    
-    - This would iterate through all windows in a real implementation
-    - For now, we'll just demonstrate the API
-    
-    - Example: Apply red border to window with ID "1"
-    srd.window.set_border_color("1", 255, 0, 0)
-    srd.window.set_border_width("1", 5)
-    
-    - Example: Apply blue border to window with ID "2"
-    srd.window.set_border_color("2", 0, 0, 255)
-    srd.window.set_border_width("2", 3)
-    
-    - Example: Disable decorations for window with ID "3"
-    srd.window.set_decorations("3", false)
-    
-    print("Test decorations applied")
-end
-
-- Call the test function
-apply_test_decorations()
-
-print("Decoration and window state test configuration loaded successfully!")