Onboarding explains the memsprout mental model before asking about Spaces

The MCP onboarding flow now always explains what memsprout is — Spaces, Topics, and Memories — before it asks how to split up your Spaces, so the questions make sense before you're asked to answer them. The space-split guidance now leads with framing Spaces as areas of expertise or ownership: if you'd expect someone to own everything about a topic, they should have a Space for it.