AI: Powered Templates tab on list creation #8

Part of #3 — AI Writing Assistance is entirely missing from the Android app

Web behaviour: the New List page has a Powered Templates tab (Subscriber only). The
user describes the list they want — e.g. "a reading list with title, author, status, and
rating" — and AI drafts a complete list structure plus a few starter rows. The user reviews,
then creates.

• Add the tab to the Android list-creation flow, hidden when the AI gate is closed.
• The generated schema must round-trip through the List Schema DSL that POST /api/lists
  accepts ({ name, description?, fields[] }, each field { key, type, label, … }).
• Starter rows arrive with the suggestion and are created alongside the list.

Tests: suggestion → schema DSL mapping; confirm → list with schema + rows created.

Filed from the parity review of feature/parity-wip @ 14d7795 against interlinedlist.com (OpenAPI /api/openapi.json, 233 paths) and the public help centre.