fix(walker): deploy elephant theme/background menus where elephant loads them

Pillar 9 VM test: the walker theme picker (and background selector)
returned "No Results". Root cause: nomarchy_themes.lua and
nomarchy_background_selector.lua (elephant lua menu providers named
"nomarchythemes" / "nomarchyBackgroundSelector") were deployed via the
bulk nomarchy config to ~/.config/nomarchy/default/elephant/ — outside
elephant's provider search path, so elephant never registered them and
`nomarchy-launch-walker -m menus:nomarchythemes` (used by nomarchy-theme,
nomarchy-wallpaper, and nomarchy-menu Style submenu) had no backing menu.

Move them into the elephant config (features/apps/elephant/config/menus/)
so they deploy to ~/.config/elephant/menus/. Verified on a fresh VM boot:
`elephant listproviders` now lists menus:nomarchythemes +
menus:nomarchyBackgroundSelector, and the walker theme picker renders all
21 palettes with per-theme preview images.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

features/apps/elephant/config/menus/nomarchy_themes.lua

@@ -0,0 +1,95 @@
+--
+-- Dynamic Nomarchy Theme Menu for Elephant/Walker
+--
+Name = "nomarchythemes"
+NamePretty = "Nomarchy Themes"
+HideFromProviderlist = true
+
+-- Check if file exists using Lua (no subprocess)
+local function file_exists(path)
+  local f = io.open(path, "r")
+  if f then
+    f:close()
+    return true
+  end
+  return false
+end
+
+-- Get first matching file from directory using ls (single call for fallback)
+local function first_image_in_dir(dir)
+  local handle = io.popen("ls -1 '" .. dir .. "' 2>/dev/null | head -n 1")
+  if handle then
+    local file = handle:read("*l")
+    handle:close()
+    if file and file ~= "" then
+      return dir .. "/" .. file
+    end
+  end
+  return nil
+end
+
+-- The main function elephant will call
+function GetEntries()
+  local entries = {}
+  local user_theme_dir = os.getenv("HOME") .. "/.config/nomarchy/themes"
+  local default_theme_dir = os.getenv("HOME") .. "/.local/share/nomarchy/themes"
+
+  local seen_themes = {}
+
+  -- Helper function to process themes from a directory
+  local function process_themes_from_dir(theme_dir)
+    -- Single find call to get all theme directories
+    local handle = io.popen("find -L '" .. theme_dir .. "' -mindepth 1 -maxdepth 1 -type d 2>/dev/null")
+    if not handle then
+      return
+    end
+
+    for theme_path in handle:lines() do
+      local theme_name = theme_path:match(".*/(.+)$")
+
+      if theme_name and not seen_themes[theme_name] then
+        seen_themes[theme_name] = true
+
+        -- Check for preview images directly (no subprocess)
+        local preview_path = nil
+        local preview_png = theme_path .. "/preview.png"
+        local preview_jpg = theme_path .. "/preview.jpg"
+
+        if file_exists(preview_png) then
+          preview_path = preview_png
+        elseif file_exists(preview_jpg) then
+          preview_path = preview_jpg
+        else
+          -- Fallback: get first image from backgrounds (one ls call)
+          preview_path = first_image_in_dir(theme_path .. "/backgrounds")
+        end
+
+        if preview_path and preview_path ~= "" then
+          local display_name = theme_name:gsub("_", " "):gsub("%-", " ")
+          display_name = display_name:gsub("(%a)([%w_']*)", function(first, rest)
+            return first:upper() .. rest:lower()
+          end)
+          display_name = display_name .. "  "
+
+          table.insert(entries, {
+            Text = display_name,
+            Preview = preview_path,
+            PreviewType = "file",
+            Actions = {
+              activate = "nomarchy-theme-set " .. theme_name,
+            },
+          })
+        end
+      end
+    end
+
+    handle:close()
+  end
+
+  -- Process user themes first (they take precedence)
+  process_themes_from_dir(user_theme_dir)
+  -- Then process default themes (only if not already seen)
+  process_themes_from_dir(default_theme_dir)
+
+  return entries
+end