memsprout moves to memsprout.com

memsprout now lives on its own domain: the app at memsprout.com, the MCP server at mcp.memsprout.com, and sign-in/authorization at auth.memsprout.com. The connect guide now shows the mcp.memsprout.com server URL. Existing connections on the old *.workers.dev / *.pages.dev URLs keep working as permanent aliases — the MCP server's OAuth discovery is host-derived, so already-connected agents are unaffected.