[finish] Cron Target Selector for Projects/Nodes

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 11 children are done: 8 PRs merged and deployed. The Automations console is reachable on dev and works well. Filed follow-ups #5707 (UX polish), #5708 (console-reference docs) and #5709 (double run row). Not verified: AC2.1 and the operator half of AC4.4, at the operator's choice.