[finish] Project memory: open the pipe, honest trust

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 6 coders (6670-6675) merged (#5601,#5628,#5627,#5612,#5625,#5647); code verified on develop, plan switch gates all runtime memory. Filed 6796 (Audit memory list off-plan). #5647 deploy pending; dev.jaah.ai unreachable, live leg unverified.