Add Omarchy-style Hyprland desktop for straylight

Ports the classic dotfiles Omarchy setup to a no-home-manager NixOS
system module (configs/omarchy.nix), scoped to straylight only so the
other desktop hosts keep i3.

- Hyprland (programs.hyprland) becomes the default lightdm session; i3
  stays enabled and selectable as a fallback.
- Omarchy config layout under ~/.config/{hypr,waybar,rofi,wlogout,
  swayosd,alacritty} symlinked from the store; mutable theme/wallpaper
  state in ~/.config/omarchy/current.
- omarchy-dots generates 8 themes (hyprland/hyprlock/waybar/rofi/
  swayosd/wlogout/alacritty/mako colour files) from each theme's
  palette, with wallpapers fetched from the Omarchy v3.8.4 tag.
- Helper scripts: omarchy-theme-set/bg-next/bg-set/apply, omarchy-menu
  (rofi power/theme/background menus), waybar toggle, screenshot, lock.
- Shared desktop modules (desktop.nix / desktop-light.nix) untouched.

configs/omarchy/wlogout/layout

@@ -0,0 +1,32 @@
+[
+  {
+    "label": "lock",
+    "action": "hyprlock",
+    "text": "Lock",
+    "keybind": "l"
+  },
+  {
+    "label": "logout",
+    "action": "hyprctl dispatch exit",
+    "text": "Logout",
+    "keybind": "e"
+  },
+  {
+    "label": "suspend",
+    "action": "systemctl suspend",
+    "text": "Suspend",
+    "keybind": "s"
+  },
+  {
+    "label": "reboot",
+    "action": "systemctl reboot",
+    "text": "Reboot",
+    "keybind": "r"
+  },
+  {
+    "label": "shutdown",
+    "action": "systemctl poweroff",
+    "text": "Shutdown",
+    "keybind": "p"
+  }
+]

configs/omarchy/wlogout/style.css

@@ -0,0 +1,27 @@
+@import "../omarchy/current/theme/wlogout.css";
+
+* {
+  background-image: none;
+  font-family: 'JetBrainsMono Nerd Font';
+  font-size: 20px;
+}
+
+window {
+  background-color: @background;
+}
+
+button {
+  color: @foreground;
+  background-color: @background;
+  border: 2px solid @foreground;
+  border-radius: 0;
+  margin: 8px;
+  padding: 24px;
+}
+
+button:focus,
+button:active,
+button:hover {
+  background-color: @accent;
+  color: @background;
+}