* feat(web): add conversation export as Markdown and JSON (#976)
Add the ability to export conversations in Markdown and JSON formats,
accessible from both the chat header and the sidebar context menu.
- Add export utility (formatThreadAsMarkdown, formatThreadAsJSON) with
support for user/assistant messages, thinking blocks, and tool calls
- Add ExportTrigger component in chat header (appears when messages exist)
- Add Export submenu to sidebar dropdown (fetches full thread state on demand)
- Add i18n translations for en-US and zh-CN
Closes#976
Made-with: Cursor
* Apply suggestions from code review
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
* Update thread creation timestamp to updated_at
---------
Co-authored-by: Willem Jiang <willem.jiang@gmail.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
