Launch the mdbase Connect beta waitlist

[callumalpass]

What changed

• add the Connect beta waitlist form and its accessible loading, success, rate-limit, and recovery states
• clarify the boundary between the open mdbase specification and the managed Connect service
• simplify the homepage and Connect explainer around ordinary Markdown, explicit app permissions, and local or hosted collections
• retire the Interop, Testbed, and Implementations marketing pages while preserving their technical artifacts and specification references
• improve the homepage animation reading treatment across desktop and mobile
• update privacy copy and site-wide calls to action to describe a waitlist rather than immediate beta access

Why

The site is ready to collect interest before general beta registration opens. Visitors should understand that joining records an email address for a future invitation and does not grant immediate access.

User impact

People can join the Connect waitlist with one email address. The managed service remains invite-only, while the open specification and local developer tools remain available without an account.

Validation

• pnpm test
• Astro diagnostics: 0 errors, warnings, or hints
• production Connect beta23 endpoint: allowed-origin preflight succeeds and invalid requests reach normal validation
• desktop and mobile waitlist-page render checks
• Impeccable detector: no findings