Add first version of online stores for wishlisted records (claude)

See docs/plans/online_stores.md

lib/music_library/online_store_templates.ex

@@ -0,0 +1,76 @@
+defmodule MusicLibrary.OnlineStoreTemplates do
+  @moduledoc """
+  The OnlineStoreTemplates context.
+  """
+
+  import Ecto.Query, warn: false
+  alias MusicLibrary.OnlineStoreTemplates.OnlineStoreTemplate
+  alias MusicLibrary.Repo
+
+  @doc """
+  Returns the list of enabled online store templates ordered by name.
+  """
+  def list_enabled_templates do
+    OnlineStoreTemplate
+    |> where([t], t.enabled == true)
+    |> order_by([t], asc: t.name)
+    |> Repo.all()
+  end
+
+  @doc """
+  Returns the list of all online store templates for management.
+  """
+  def list_templates do
+    OnlineStoreTemplate
+    |> order_by([t], asc: t.name)
+    |> Repo.all()
+  end
+
+  @doc """
+  Gets a single online store template.
+  """
+  def get_template!(id), do: Repo.get!(OnlineStoreTemplate, id)
+
+  @doc """
+  Creates an online store template.
+  """
+  def create_template(attrs \\ %{}) do
+    %OnlineStoreTemplate{}
+    |> OnlineStoreTemplate.changeset(attrs)
+    |> Repo.insert()
+  end
+
+  @doc """
+  Updates an online store template.
+  """
+  def update_template(%OnlineStoreTemplate{} = template, attrs) do
+    template
+    |> OnlineStoreTemplate.changeset(attrs)
+    |> Repo.update()
+  end
+
+  @doc """
+  Deletes an online store template.
+  """
+  def delete_template(%OnlineStoreTemplate{} = template) do
+    Repo.delete(template)
+  end
+
+  @doc """
+  Returns an `%Ecto.Changeset{}` for tracking online store template changes.
+  """
+  def change_template(%OnlineStoreTemplate{} = template, attrs \\ %{}) do
+    OnlineStoreTemplate.changeset(template, attrs)
+  end
+
+  @doc """
+  Generates a URL from a template by replacing variables with record data.
+  """
+  def generate_url(template, record) do
+    artists_string = Enum.map_join(record.artists, " ", & &1.name)
+
+    template.url_template
+    |> String.replace("{artist}", URI.encode(artists_string))
+    |> String.replace("{title}", URI.encode(record.title))
+  end
+end