feat: add dark mode support, accordion UI, and current combination display

- Update Theme Studio sidebar to use DaisyUI theme-aware classes for dark mode
- Convert Customise accordion to native details/summary elements for proper interaction
- Add "Current combination" card showing active theme settings
- Add SVG recolorer for logo color customization
- Add image controller for serving uploaded images
- Implement header background image controls (zoom, position)
- Add toggle_customise event handler to preserve accordion state across re-renders

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

lib/simpleshop_theme/theme/presets.ex

@@ -93,6 +93,21 @@ defmodule SimpleshopTheme.Theme.Presets do
     }
   }
 
+  @descriptions %{
+    gallery: "Elegant & editorial",
+    studio: "Clean & professional",
+    boutique: "Warm & sophisticated",
+    bold: "High contrast, strong",
+    playful: "Fun & approachable",
+    minimal: "Understated & modern",
+    night: "Dark & dramatic",
+    classic: "Traditional & refined",
+    impulse: "Light & airy"
+  }
+
+  # Core keys used to match presets (excludes branding-specific settings)
+  @core_keys ~w(mood typography shape density grid_columns header_layout accent_color)a
+
   @doc """
   Returns all available presets.
 
@@ -132,4 +147,72 @@ defmodule SimpleshopTheme.Theme.Presets do
   def list_names do
     Map.keys(@presets)
   end
+
+  @doc """
+  Gets the description for a preset.
+
+  ## Examples
+
+      iex> get_description(:gallery)
+      "Elegant & editorial"
+
+  """
+  def get_description(preset_name) when is_atom(preset_name) do
+    Map.get(@descriptions, preset_name, "")
+  end
+
+  @doc """
+  Returns all presets with their descriptions.
+
+  ## Examples
+
+      iex> all_with_descriptions()
+      [{:bold, "High contrast, strong"}, ...]
+
+  """
+  def all_with_descriptions do
+    @presets
+    |> Map.keys()
+    |> Enum.sort()
+    |> Enum.map(fn name -> {name, Map.get(@descriptions, name, "")} end)
+  end
+
+  @doc """
+  Detects which preset matches the current theme settings, if any.
+  Only compares core theme keys, ignoring branding-specific settings.
+
+  ## Examples
+
+      iex> detect_preset(%ThemeSettings{mood: "warm", typography: "editorial", ...})
+      :gallery
+
+      iex> detect_preset(%ThemeSettings{...customized...})
+      nil
+
+  """
+  def detect_preset(theme_settings) do
+    current_core = extract_core_values(theme_settings)
+
+    Enum.find_value(@presets, fn {name, preset} ->
+      preset_core = Map.take(preset, @core_keys)
+
+      if maps_match?(current_core, preset_core) do
+        name
+      else
+        nil
+      end
+    end)
+  end
+
+  defp extract_core_values(theme_settings) do
+    theme_settings
+    |> Map.from_struct()
+    |> Map.take(@core_keys)
+  end
+
+  defp maps_match?(map1, map2) do
+    Enum.all?(@core_keys, fn key ->
+      Map.get(map1, key) == Map.get(map2, key)
+    end)
+  end
 end