[finish] Add Timesheet Reports Settings Help Page

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.

Verified: both coders merged (PR #44, #45), gate green; the Help page and its Help link are live on dev on all 4 pages and legible at 1280 and 360, light and dark. No gaps, so no follow-up filed.