fix(waybar): drop 4 broken per-palette style.css overrides

themes/{catppuccin,lumon,nord,retro-82}/style.css fully replaced the
default style.css (no @import) but defined only 2–14 lines — just
@define-color declarations and, for nord, a minimal window#waybar block.
The default style ships ~110 lines covering #workspaces, #tray, #cpu,
#custom-nomarchy's Nomarchy-font override, margins/padding, the indicator
.active states, etc. So picking any of those four palettes produced a
waybar with zero structural styling.

The default style at features/desktop/waybar/config/style.css already
@imports ../nomarchy/current/theme/waybar.css — which themes/engine/
files.nix:30-34 generates with @background/@foreground/@accent from the
active palette. So removing the broken overrides restores per-palette
colors via the default-style path. summer-day and summer-night are kept
because their 100+-line style.css files are intentional, self-contained
visual redesigns (the case the themes/engine/loader.nix:76-79 comment
explicitly carves out for "themes that need significantly different
styling").

features/desktop/waybar/themes/catppuccin/style.css

@@ -1,2 +0,0 @@
-@define-color foreground #cdd6f4;
-@define-color background #181824;

features/desktop/waybar/themes/lumon/style.css

@@ -1,2 +0,0 @@
-@define-color foreground #d6e2ee;
-@define-color background #213442;

features/desktop/waybar/themes/nord/style.css

@@ -1,14 +0,0 @@
-@define-color background #2e3440;
-@define-color foreground #d8dee9;
-@define-color accent #88c0d0;
-
-/* Base style for Nord */
-* {
-  font-family: JetBrainsMono Nerd Font, FontAwesome;
-  font-size: 13px;
-}
-
-window#waybar {
-  background-color: @background;
-  color: @foreground;
-}

features/desktop/waybar/themes/retro-82/style.css

@@ -1,3 +0,0 @@
-@define-color bg #00172e;
-@define-color foreground #f6dcac;
-@define-color background alpha(@bg, 0.8);