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

script/omarchy-theme-bg-next

@@ -1,20 +1,22 @@
-#!/bin/sh -e
+#!/bin/bash
 
-# Cycles through the background images available
+# omarchy:summary=Cycle to the next background for the current theme
+# omarchy:examples=omarchy theme bg next
 
-THEMES_DIR="$HOME/.local/share/themes"
-BACKGROUNDS_DIR="${THEMES_DIR}/current/theme/backgrounds/"
-CURRENT_BACKGROUND_LINK="${THEMES_DIR}/current/background"
+THEME_NAME=$(cat "$HOME/.config/omarchy/current/theme.name" 2>/dev/null)
+THEME_BACKGROUNDS_PATH="$HOME/.config/omarchy/current/theme/backgrounds/"
+USER_BACKGROUNDS_PATH="$HOME/.config/omarchy/backgrounds/$THEME_NAME/"
+CURRENT_BACKGROUND_LINK="$HOME/.config/omarchy/current/background"
 
-mapfile -d '' -t BACKGROUNDS < <(find "$BACKGROUNDS_DIR" -type f -print0 | sort -z)
+mapfile -d '' -t BACKGROUNDS < <(find -L "$USER_BACKGROUNDS_PATH" "$THEME_BACKGROUNDS_PATH" -maxdepth 1 -type f -print0 2>/dev/null | sort -z)
 TOTAL=${#BACKGROUNDS[@]}
 
-if [[ $TOTAL -eq 0 ]]; then
+if (( TOTAL == 0 )); then
   notify-send "No background was found for theme" -t 2000
   setsid uwsm app -- awww clear >/dev/null 2>&1 &
 else
   # Get current background from symlink
-  if [[ -L "$CURRENT_BACKGROUND_LINK" ]]; then
+  if [[ -L $CURRENT_BACKGROUND_LINK ]]; then
     CURRENT_BACKGROUND=$(readlink "$CURRENT_BACKGROUND_LINK")
   else
     # Default to first background if no symlink exists
@@ -24,14 +26,14 @@ else
   # Find current background index
   INDEX=-1
   for i in "${!BACKGROUNDS[@]}"; do
-    if [[ "${BACKGROUNDS[$i]}" == "$CURRENT_BACKGROUND" ]]; then
+    if [[ ${BACKGROUNDS[$i]} == $CURRENT_BACKGROUND ]]; then
       INDEX=$i
       break
     fi
   done
 
   # Get next background (wrap around)
-  if [[ $INDEX -eq -1 ]]; then
+  if (( INDEX == -1 )); then
     # Use the first background when no match was found
     NEW_BACKGROUND="${BACKGROUNDS[0]}"
   else