Product update

This release makes Notch multiplayer and introduces the AI assistant.

Added

• Comments on drawings — Click anywhere on a sheet to start a pinned thread. Threads collect in the Discussion panel, @mentions notify teammates, and authors can drag their pins to reposition them.
• Real-time collaboration — Presence avatars, live selections in each person's color, markups appearing for everyone as they're drawn, and a follow mode for walking a group through a set. On for every document, with nothing to set up.
• Notch AI — An assistant panel in the editor. It indexes your drawing set, answers questions with clickable sheet references, and detects each page's drawing scale automatically. Any change it proposes requires your approval before it happens.

Changed

• Uploads — A simpler two-click flow with real per-file progress bars. Size caps for uploads, imports, and exports raised substantially.