feat: category filter includes subcategories

lib/components_elixir/inventory.ex

@@ -203,6 +203,27 @@ defmodule ComponentsElixir.Inventory do
     Category.changeset(category, attrs)
   end
 
+  @doc """
+  Gets all category IDs that are descendants of the given category ID, including the category itself.
+  This is used for filtering components by category and all its subcategories.
+  Returns an empty list if the category doesn't exist.
+
+  Note: This implementation loads all categories into memory for traversal, which is efficient
+  for typical category tree sizes (hundreds of categories). For very large category trees,
+  a recursive CTE query could be used instead.
+  """
+  def get_category_and_descendant_ids(category_id) when is_integer(category_id) do
+    categories = list_categories()
+
+    # Verify the category exists before getting descendants
+    case Enum.find(categories, &(&1.id == category_id)) do
+      nil -> []
+      _category -> ComponentsElixir.Inventory.Hierarchical.descendant_ids(categories, category_id, &(&1.parent_id))
+    end
+  end
+
+  def get_category_and_descendant_ids(_), do: []
+
   ## Components
 
   @doc """
@@ -219,7 +240,9 @@ defmodule ComponentsElixir.Inventory do
   defp apply_component_filters(query, opts) do
     Enum.reduce(opts, query, fn
       {:category_id, category_id}, query when not is_nil(category_id) ->
-        where(query, [c], c.category_id == ^category_id)
+        # Get the category and all its descendant category IDs
+        category_ids = get_category_and_descendant_ids(category_id)
+        where(query, [c], c.category_id in ^category_ids)
 
       {:storage_location_id, storage_location_id}, query when not is_nil(storage_location_id) ->
         where(query, [c], c.storage_location_id == ^storage_location_id)