Add an AI button in the page byline that generates a note's title from the
live editor content (including unsaved edits) and applies it immediately.
Server: one-shot, non-streaming POST /ai-chat/generate-page-title mirroring
the chat generateTitle path — gated by settings.ai.generative, throttled via
AI_CHAT_THROTTLER, resolves the workspace chat model and returns { title }.
The endpoint never touches the page; the client applies the title through the
existing /pages/update route (which enforces edit permission).
Client: ai-chat-service.generatePageTitle, a useGeneratePageTitle hook that
converts the editor HTML to markdown, calls the endpoint, applies the title
via updateTitle + updatePageData, reflects it in the unfocused title editor,
and broadcasts the UpdateEvent (mirroring TitleEditor.saveTitle). A sparkles
button (GenerateTitleGroup) renders next to dictation, edit-mode + flag gated.
Tests: pure cleanGeneratedTitle helper + controller gate/delegation/error-map.
i18n: en-US + ru-RU strings.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>