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/hypr/looknfeel.conf

@@ -0,0 +1,131 @@
+# Omarchy v3 default/hypr/looknfeel.conf.
+# Default border colours here are overridden by the active theme's
+# hyprland.conf (sourced last from hyprland.conf).
+
+# Variables
+$activeBorderColor = rgba(33ccffee) rgba(00ff99ee) 45deg
+$inactiveBorderColor = rgba(595959aa)
+
+general {
+    gaps_in = 5
+    gaps_out = 10
+
+    border_size = 2
+
+    col.active_border = $activeBorderColor
+    col.inactive_border = $inactiveBorderColor
+
+    # Set to true enable resizing windows by clicking and dragging on borders and gaps
+    resize_on_border = false
+
+    # Please see https://wiki.hypr.land/Configuring/Advanced-and-Cool/Tearing/ before you turn this on
+    allow_tearing = false
+
+    layout = dwindle
+}
+
+decoration {
+    rounding = 0
+
+    shadow {
+        enabled = true
+        range = 2
+        render_power = 3
+        color = rgba(1a1a1aee)
+    }
+
+    blur {
+        enabled = true
+        size = 2
+        passes = 2
+        special = true
+        brightness = 0.60
+        contrast = 0.75
+    }
+}
+
+group {
+    col.border_active = $activeBorderColor
+    col.border_inactive = $inactiveBorderColor
+    col.border_locked_active = $activeBorderColor
+    col.border_locked_inactive = $inactiveBorderColor
+
+    groupbar {
+        font_size = 12
+        font_family = monospace
+        font_weight_active = ultraheavy
+        font_weight_inactive = normal
+
+        indicator_height = 0
+        indicator_gap = 5
+        height = 22
+        gaps_in = 5
+        gaps_out = 0
+
+        text_color = rgb(ffffff)
+        text_color_inactive = rgba(ffffff90)
+        col.active = rgba(00000040)
+        col.inactive = rgba(00000020)
+
+        gradients = true
+        gradient_rounding = 0
+        gradient_round_only_edges = false
+    }
+}
+
+animations {
+    enabled = yes, please :)
+
+    bezier = easeOutQuint,0.23,1,0.32,1
+    bezier = easeInOutCubic,0.65,0.05,0.36,1
+    bezier = linear,0,0,1,1
+    bezier = almostLinear,0.5,0.5,0.75,1.0
+    bezier = quick,0.15,0,0.1,1
+
+    animation = global, 1, 10, default
+    animation = border, 1, 5.39, easeOutQuint
+    animation = windows, 1, 3.79, easeOutQuint
+    animation = windowsIn, 1, 4.1, easeOutQuint, popin 87%
+    animation = windowsOut, 1, 1.49, linear, popin 87%
+    animation = fadeIn, 1, 1.73, almostLinear
+    animation = fadeOut, 1, 1.46, almostLinear
+    animation = fade, 1, 3.03, quick
+    animation = layers, 1, 3.81, easeOutQuint
+    animation = layersIn, 1, 4, easeOutQuint, fade
+    animation = layersOut, 1, 1.5, linear, fade
+    animation = fadeLayersIn, 1, 1.79, almostLinear
+    animation = fadeLayersOut, 1, 1.39, almostLinear
+    animation = workspaces, 0, 0, ease
+    animation = specialWorkspace, 1, 3, easeOutQuint, slidevert
+}
+
+dwindle {
+    preserve_split = true
+    force_split = 2
+}
+
+scrolling {
+    column_width = 0.49
+}
+
+master {
+    new_status = master
+}
+
+misc {
+    disable_hyprland_logo = true
+    disable_splash_rendering  = true
+    disable_scale_notification = true
+    focus_on_activate = true
+    anr_missed_pings = 3
+    on_focus_under_fullscreen = 1
+}
+
+cursor {
+    hide_on_key_press = true
+    warp_on_change_workspace = 1
+}
+
+binds {
+    hide_special_on_workspace_change = true
+}