[finish] Refactor Large Modules Into Smaller Modules

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 21 split children done and merged; develop has no file over 3,000 lines, no shims, and the splits are deployed with the dev UI working. One gap filed as follow-up 7719: the operator_settings split left an AttributeError in trigger_intake and stale test patches, so develop's gate is red.