Cooking assistant's fullscreen mode gets a real left sidebar (always-
visible conversation list, hover-reveal rename/delete) on desktop
(md+), replacing the small dropdown menu that made sense in the narrow
420px drawer but not in a full-viewport layout. Mobile fullscreen and
the normal drawer keep the dropdown (ConversationMenu) — no room for a
persistent sidebar there.
Extracted the shared fetch/rename/delete/create logic into
use-conversation-list.ts so the dropdown (ConversationMenu) and the new
sidebar (ConversationSidebar) can't silently diverge — both are thin
render layers over the same hook. ConversationMenu gained an optional
className prop so the panel can hide it with `md:hidden` specifically
when the sidebar is already covering that job.
Per-recipe chat is untouched — it's single-threaded by design and never
used either of these components.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>