PhoenixKitWeb.Components.AITranslate.FormBinding for projects forms — the
storage-specific half of the shared AI-translate glue.
Projects store translations in a translations JSONB column shaped
%{lang => %{field => value}} with plain field keys (the form binds them
directly). The translatable fields differ per resource type — project/
template (name + description), task (title + description), assignment
(description) — read from each schema's translatable_fields/0.