Claude and ChatGPT connect guides

New

• Connect guides on the site -- new step-by-step pages at /connect-claude and /connect-chatgpt with recreated agent-UI previews, copy-URL actions, and prefilled magic-link buttons; linked from the footer.
• MCP page connect walkthroughs -- guided step-by-step dialogs for ChatGPT (enable Developer mode, create connector, prefilled setup chat with UI previews) and Claude (connect card, Continue in Claude prompt), plus a two-step how-to on the page.
• Post-onboarding tour on mobile -- the walkthrough now runs on phones and adds a final Context step after MCP, Chat, and Connections.

Improved

• ChatGPT connector links -- the create-connector link now works from the in-app MCP page, auth and onboarding agent popups, and the marketing site (the old #settings/Connectors deep link no longer worked).