Current chat answers only reference the currently open page. This change adds a user-selectable scope so questions can be answered from either the current page or the entire current language, with AI routing to the most relevant page using that language’s TOC.

• Scope selection in chat UI

  • Added radio options to the chat form:
    • このページの内容について質問
    • （言語名）全体について質問
  • Sends questionScope: "page" | "language" with chat requests.

• Language-wide routing flow in /api/chat

  • For questionScope === "language":
    • Builds a routing prompt from the current language’s page list + section titles.
    • Asks AI to return the most relevant page slug (or null).
    • Loads routed page sections and uses them as chat context.
  • For questionScope === "page":
    • Preserves existing behavior (current page sections).

• Chat event payload and cache revalidation alignment

  • Extended initial stream event with pagePath of the actual routed target.
  • Client now revalidates chat against the routed page path, not always the current page.
  • Keeps section scroll behavior only when routed page matches current page.

// request payload
body: JSON.stringify({
  path,
  userQuestion,
  questionScope, // "page" | "language"
  sectionContent,
  replOutputs,
  files,
  execResults,
})

// streamed chat-start event
{ type: "chat", chatId, sectionId, pagePath }