refactor(media): use UUID instead of ID for media retrieval in GraphQL

Fixes #1760

priv/repo/migrations/20250521145952_add_uuid_to_media.exs

@@ -0,0 +1,12 @@
+defmodule Mobilizon.Storage.Repo.Migrations.AddUuidToMedia do
+  use Ecto.Migration
+
+  def change do
+    # Create the new uuid for medias
+    alter table(:medias) do
+      add :uuid, :uuid, default: fragment("gen_random_uuid()"), null: false
+    end
+
+    create(unique_index(:medias, [:uuid]))
+  end
+end