[finish] Jarvis Website Product Assistant Feasibility

Terminal analytical phase: verify every build subtask has completed and resolved, optionally note UI acceptance evidence, then settle. Dispatched as a read-only runner role (feat/finish-as-runner, ADR-0040) whose settle is server-computed (`task.settle` declaring a `finish` terminal) — the server derives the full finish report and flips this child `-> done`; the runner attests nothing. Readied by the fan-out sweep like its siblings; its dependency edges to every coder keep `dispatchable_tasks` from dispatching it until those deps are done.

All 10 children done; 7 PRs (#4542–#4558) merged to develop. jaah.ai embed is owed in the sales project (operator owns it). Follow-up 5185 must be deleted in the console; delete was refused 403.