fix production deployment: CSS, images and theme seeding

- Add @source for shop_components/ directory in app-shop.css (Tailwind
  wasn't scanning sub-modules after the refactor, dropping ~73 utilities)
- Remove overly aggressive .dockerignore rules that excluded mockup
  image variants needed by the responsive_image component
- Seed default theme settings on first boot via Release.seed_defaults/0
  in the supervision tree (seeds.exs doesn't run in releases)
- Fix PDP gallery images for mock data by appending -1200.webp to
  bare mockup base paths
- Update fly.toml format from fly launch

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

lib/simpleshop_theme/application.ex

@@ -12,6 +12,8 @@ defmodule SimpleshopTheme.Application do
       SimpleshopTheme.Repo,
       {Ecto.Migrator,
        repos: Application.fetch_env!(:simpleshop_theme, :ecto_repos), skip: skip_migrations?()},
+      # Seed default theme settings if none exist (first boot)
+      Supervisor.child_spec({Task, &SimpleshopTheme.Release.seed_defaults/0}, id: :seed_defaults),
       # Load encrypted secrets from DB into Application env
       {Task, &SimpleshopTheme.Secrets.load_all/0},
       {DNSCluster, query: Application.get_env(:simpleshop_theme, :dns_cluster_query) || :ignore},

lib/simpleshop_theme/release.ex

@@ -16,6 +16,25 @@ defmodule SimpleshopTheme.Release do
     end
   end
 
+  @doc """
+  Seeds default theme settings if none exist.
+
+  Called on every boot but only writes to the DB on first run
+  (when the settings table is empty). Safe to call repeatedly.
+  """
+  def seed_defaults do
+    alias SimpleshopTheme.Settings
+
+    case Settings.get_setting("theme_settings") do
+      nil ->
+        {:ok, _} = Settings.apply_preset(:studio)
+        :ok
+
+      _exists ->
+        :ok
+    end
+  end
+
   def rollback(repo, version) do
     load_app()
     {:ok, _, _} = Ecto.Migrator.with_repo(repo, &Ecto.Migrator.run(&1, :down, to: version))