Add MCP QuickAdd buttons to landing page and public profile page

[robinsadeghpour]

Summary

Surface MCP QuickAdd actions on public-facing pages so developers can start using OneContext instantly.

Tasks

• Add "Add to Cursor" / "Add to Claude Code" CTAs to the landing page hero or developer section
• Add QuickAdd buttons to public profile pages (e.g. onecontext.dev/u/username)
• Handle unauthenticated flow — prompt sign-up first, then redirect back to setup
• Design the buttons to match brand guidelines

Context

Public pages are a key discovery surface. Making MCP setup accessible from these pages shortens the path from "interesting" to "installed."