feat: add image metadata fields for optimization pipeline

- Add source_width, source_height, variants_status fields to images table
- Remove thumbnail_data (now derived to disk cache)
- Add Oban tables via Oban.Migration.up(version: 12)
- Update Image schema changeset to include new fields

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

lib/simpleshop_theme/media/image.ex

@@ -13,7 +13,9 @@ defmodule SimpleshopTheme.Media.Image do
     field :data, :binary
     field :is_svg, :boolean, default: false
     field :svg_content, :string
-    field :thumbnail_data, :binary
+    field :source_width, :integer
+    field :source_height, :integer
+    field :variants_status, :string, default: "pending"
 
     timestamps(type: :utc_datetime)
   end
@@ -23,7 +25,18 @@ defmodule SimpleshopTheme.Media.Image do
   @doc false
   def changeset(image, attrs) do
     image
-    |> cast(attrs, [:image_type, :filename, :content_type, :file_size, :data, :is_svg, :svg_content])
+    |> cast(attrs, [
+      :image_type,
+      :filename,
+      :content_type,
+      :file_size,
+      :data,
+      :is_svg,
+      :svg_content,
+      :source_width,
+      :source_height,
+      :variants_status
+    ])
     |> validate_required([:image_type, :filename, :content_type, :file_size, :data])
     |> validate_inclusion(:image_type, ~w(logo header product))
     |> validate_number(:file_size, less_than: @max_file_size)

priv/repo/migrations/20260121220351_add_image_metadata_and_oban.exs

@@ -0,0 +1,15 @@
+defmodule SimpleshopTheme.Repo.Migrations.AddImageMetadataAndOban do
+  use Ecto.Migration
+
+  def change do
+    alter table(:images) do
+      add :source_width, :integer
+      add :source_height, :integer
+      add :variants_status, :string, default: "pending"
+
+      remove :thumbnail_data
+    end
+
+    Oban.Migration.up(version: 12)
+  end
+end