Start a Flows custom app

Get a clickable https://localhost prototype running quickly. The user story, data-model curiosity, and App-Brief.md can proceed in parallel after localhost is up. Missing appHostingAcl WRITE is a parallel track, not a gate.

The Fusion prompt already covers the folder check, apps create and auth login with CDF flags filled in, "createdVia", apps skills pull, serving https://localhost:<port>, and this project's MCP command. Run those commands as given; do not re-ask org, project, cluster, or base URL. If browser login stalls, loops, or never persists a session, stop and ask the builder. This skill picks up from there.

Do not dump an empty App-Brief template as the opening move. Do not invent mkcert / brew / choco steps. Do not paste this skill body back into chat.

If a Fusion Custom apps prompt set "createdVia" on app.json, leave that field as-is.