refactor: migrate to template-based theme system, clean up old per-theme configs

- Remove per-theme app configs (alacritty, foot, ghostty, hyprland,
  hyprlock, mako, rofi, swayosd, tmux, walker, waybar, etc.) now
  handled by default/themed/ templates
- Update omarchy scripts (bg-next, list, set) for new template flow
- Update configs: bootstrap, nvim, rofi, tmux, mako
- Tweak installers (02-install-base.sh, btop, desktop, goose, nvim,
  obsidian, theme, tmux)
- Remove obsolete hyprland-rofi-* and hyprland-walker-* scripts
- Update neovim.lua across remaining themes

themes/kanagawa/hyprland.conf

@@ -1,3 +1,12 @@
+$activeBorderColor = rgb(dcd7ba)
+
 general {
-    col.active_border = rgb(dcd7ba)
+    col.active_border = $activeBorderColor
 }
+
+group {
+    col.border_active = $activeBorderColor
+}
+
+# Kanagawa backdrop is too strong for detault opacity
+windowrule = opacity 0.98 0.95, match:tag terminal