The welcome tour is now a real tour

The first-run welcome tour no longer reads you four slides in a modal. It now walks the actual app: each step spotlights the real region it's describing — the capture composer, the Shared Spaces nav, your Topics, the Settings entry for connecting agents — with a small popover anchored beside it. Next/Back/Skip and a step counter, Esc to skip, arrow keys to move, and the final "Get started" lands you on your Personal Space home.