Docs site and affiliate program

A written guide replaces the blog and the directory, and referrals now get attributed at checkout.

• Docs at /docs: quickstart, briefing, metrics, dashboard, integrations, alerts and troubleshooting, plus API, CLI and MCP references.
• Affiliate program through Endorsely — the referral id travels into Stripe checkout, so a signup is credited to whoever sent it.
• The blog and the product directory are gone; their URLs redirect into the docs.