Dashboard tour

The embedded admin dashboard (React + Vite + TanStack + shadcn/ui) groups collections in the sidebar, opens each into a type-aware records table, and edits fields through per-type panels with an inline syntax-help popover on every rule input. Collection Import/export round-trips the same JSON shape Schema as code uses, so a collection built by hand in the dashboard can be checked into version control the same way a hand-written one can.