docs: add changelog entry for the composable AskAiChat parts

[devin-ai-integration]

Summary

AskAiChat from @fern-api/search-widget can now be split into three parts: AskAiChat.Root (state and config), AskAiChat.Trigger (a real button), and AskAiChat.Panel (the chat). That matters to customers because the Ask AI entry point can now live anywhere in their own app — a help dropdown, a command palette, a link, a table row — while the chat panel sits outside the menu, so closing the menu no longer tears the chat down. They can also drive the panel's open state from their own code (open / defaultOpen / onOpenChange, plus trigger="none" for no built-in button at all).

The page content for all of this already landed in #6684, which documented search-widget 0.3.0 on the Ask AI chat panel page (composable parts, controlled-open props, trigger="none", and AskAiChat.Sparkles). I verified that page against the shipped types/index.d.ts on app and every component name, prop name, type, and default matches, so this PR adds the one thing that was missing: the Docs changelog entry.

Implements docs for: fix(docs): support an Ask AI trigger inside a Radix dropdown menu (fern-api/fern-platform#14119)

Details

• Added fern/products/docs/pages/changelog/2026-08-20.mdx — one ## entry tagged ai, search (matching the AskAiChat launch entry on 2026-08-17), covering the composable parts, the controlled-open props, trigger="none", and AskAiChat.Sparkles, with the CTA linking to the #custom-triggers section of the chat panel page.

No page changes: fern/products/docs/pages/ask-fern/ask-ai-chat.mdx and the standalone widgets overview already cover this API correctly.

Vale reports 0 errors/warnings/suggestions on the new file, and fern check --warnings finds 0 errors (the 8 warnings are preexisting and unrelated: endpoint path conflicts, two generator config pages, an unreachable FDR redirect check, and the accent contrast ratio).

Link to Devin session: https://app.devin.ai/sessions/745c67a40d914dfeb7e17f4c6511ed40

[devin-ai-integration]

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[github-actions]

🌿 Preview your docs: https://fern-preview-devin-1787418542-askaichat-composable-changelog.docs.buildwithfern.com/learn

Here are the markdown pages you've updated:

• learn/docs/changelog/2026/8/20