Improve metadata storage (#37)

* Updated config path to specify metadata storage path

* Removed metadata column from DB, replacing it with filepath columns

* Updated app to store compressed metadata; automatically download thumbnails

* Ensured metadata is deleted when other files are deleted

* Updated docs

* Added inets to application start so http calls work in prod

priv/repo/migrations/20240223184259_add_metadata_filepath_to_media_metadata.exs

@@ -0,0 +1,12 @@
+defmodule Pinchflat.Repo.Migrations.AddMetadataFilepathToMediaMetadata do
+  use Ecto.Migration
+
+  def change do
+    alter table(:media_metadata) do
+      add :metadata_filepath, :string, null: false
+      add :thumbnail_filepath, :string, null: false
+
+      remove :client_response, :json
+    end
+  end
+end