[finish] ACP runtime: every provider lane on ACP

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.complete` 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 8 coders merged (#6046,#6050,#6051,#6058,#6061,#6065,#6067,#6074). Gap rows and jaah_account legacy row are gone, provider-branches OK, replay tests pass, Providers on dev correct. Dev acceptance runs are owed: filed 7642 (Gemini) and 7643 (Jaah-account). UX fix filed as 7644. Full gate is owned by 7544.