Replace Rofi with Walker as application launcher

Walker (GTK4 + Elephant backend) replaces rofi-lbonn-wayland-git as the
central launcher and menu framework.

Native Walker providers replace 5 custom rofi scripts:
- App launcher (desktopapplications provider)
- Clipboard (clipboard provider, replaces cliphist frontend)
- Bluetooth (bluetooth provider, replaces bluetoothctl script)
- Volume/audio (wireplumber provider)
- Sink switcher (wireplumber provider)

3 scripts ported to Walker dmenu mode:
- moonarch-vpn (nmcli)
- moonarch-cpugov (auto-cpufreq)
- moonarch-sink-switcher (pactl)

Settings menu (moonarch-setmen) removed — apps are findable via Walker
app search directly.

Walker theme (gtk-inherit) inherits all colors from the active GTK4
theme instead of hardcoding Catppuccin values.

Walker and Elephant run as systemd user services for instant startup.

Also standardizes GTK theme to Colloid-Grey-Dark-Catppuccin across all
config files (was inconsistent between gsettings and file configs).

Old rofi configs preserved in legacy/rofi/ for reference.

legacy/rofi/colors.rasi

@@ -0,0 +1,82 @@
+/**
+ * @author Dominik Kressler
+ * @package rofi-archer
+ * @version 1.0.0
+ **/
+
+* {
+    background:     #1e1e2e;
+    background-alt: #eff1f580;
+
+
+
+    foreground:     #eff1f5;
+    selected:       #4c566a;
+    border:         #eff1f5;
+    active:         #98C37988;
+    urgent:         var(error-color);
+
+
+
+    /*https://catppuccin.ryanccn.dev/palette*/
+    rosewater:      #f5e0dc;
+    flamingo:       #f2cdcd;
+    pink:           #f5c2e7;
+    mauve:          #cba6f7;
+    red:            #f38ba8;
+    maroon:         #eba0ac;
+    peach:          #fab387;
+    yellow:         #f9e2af;
+    green:          #a6e3a1;
+    teal:           #94e2d5;
+    sky:            #89dceb;
+    sapphire:       #74c7ec;
+    blue:           #89b4fa;
+    lavender:       #b4befe;
+
+    text:           #eff1f5;
+    subtext1:       #eff1f580;
+    subtext0:       #a6adc8;
+
+    overlay0:       #6c7086;
+    overlay1:       #7f849c;
+    overlay2:       #9399b2;
+
+    surface0:       #313244;
+    surface1:       #45475a;
+    surface2:       #585b70;
+
+    base:           #1e1e2e;
+    mantle:         #181825;
+    crust:          #11111b;
+
+
+
+    /* GTK THEME VARS*/
+    theme-fg-color: #eff1f5;
+    theme-text-color: #eff1f5;
+    theme-bg-color: #1e1e2e;
+    theme-base-color: #1e1e2e;
+
+    theme-bg-color-shade-1: #1e1e2eEF;
+    theme-bg-color-shade-2: #1e1e2eD8;
+    theme-bg-color-shade-3: #1e1e2eC9;
+
+    theme-selected-bg-color: #b4befe;
+    theme-selected-fg-color: #11111b;
+    
+    theme-unfocused-fg-color: #eff1f5;
+    theme-unfocused-text-color: #eff1f5;
+    theme-unfocused-bg-color: #1e1e2e;
+    theme-unfocused-base-color: #1e1e2e;
+    theme-unfocused-selected-bg-color: #b4befe;
+    theme-unfocused-selected-fg-color: #11111b;
+    unfocused-insensitive-color: #eff1f5;
+    
+    borders: #b4befe30;
+    unfocused-borders: #eff1f5;
+    
+    warning-color: #f9e2af;
+    error-color: #f38ba8;
+    success-color: #a6e3a1;
+}