feat: export chat conversation as Markdown or PDF

[Harigithub11]

Summary

Users should be able to export the full chat conversation as a Markdown (.md) file or a PDF directly from the chat UI — no backend changes needed.

Current Behavior

The Navbar has a Share button for sending conversations via email or public link. There is no option to download or export the conversation locally.

Expected Behavior

A dropdown export button in the Navbar (next to the Share button) with two options:

• Export as Markdown — downloads a .md file with all messages formatted cleanly.
• Export as PDF — triggers the browser's native print/save-as-PDF dialog with a readable layout.

Where to Look

Primary file: app/(main)/chat/[chatId]/components/Navbar.tsx

• The Share button lives around line 334. Add the export dropdown in the same button group.
• The conversationId is already derivable from usePathname() — same pattern used on line 69.
• The chat title is available in the displayTitle state (line 63) — use it for the filename.

Fetching messages: services/ChatService.ts

• ChatService.loadMessages(conversationId, start, limit) (line 569) fetches existing conversation messages. Use this to retrieve the full conversation before exporting.

UI component: components/ui/dropdown-menu.tsx is already available for the dropdown.

For Markdown — format the messages into text, create a Blob, and trigger a download via a temporary anchor element.

For PDF — no external library needed. Build a styled HTML representation of the conversation and use the browser's built-in print functionality.

Files to Change

File	What changes
app/(main)/chat/[chatId]/components/Navbar.tsx	Add export dropdown button and the two export handler functions

No backend changes. No new npm dependencies.