chore(task-board): mothball it; superseded by the High Seat and ledger

Operator ruling 2026-09-24. On ana-docker the stack is `docker compose
down`: the container is removed and port 7878 is closed. Kept for revival:
- the data dir /opt/docker/conf/task-board/data (tasks.db, last written
  2026-09-11)
- the task-board:local image
- stacks/task-board/ and the host's compose + .env

The Uptime Kuma monitor (id 3) was deleted before the stop so it could
not page, and its row is removed from monitors.yaml. Homepage drops the
card on its own, since it reads the container's labels.

Hooks: the container log showed no hook POSTs in 30 days. The only
traffic was open browser tabs holding /events, and the plugin was already
uninstalled on nh3-dev. Removed the paragraph that told sessions to call
task_* tools (CLAUDE.md, and the fork-fleet.sh template that seeds new
repos), the vestigial TASK_BOARD_SESSION env in .claude/settings.json, and
the listings in README and FLEETTOOLS.

scripts/fork-fleet.sh

@@ -97,24 +97,6 @@ structured pass/change/fail reporting, idempotency via
 \`creates:\` / \`when:\` / \`changed_when:\`. Template:
 [\`playbooks/elway-smoke.yaml\`](playbooks/elway-smoke.yaml).
 
-**Task visibility via task-board.** If the Claude Code session has the
-\`task-board\` plugin enabled (installed from
-\`git@gitea.phasefinal.com:vh/task-board.git\`), a card tracks work
-in progress. Hooks flip the card on turn boundaries automatically;
-call \`task_start\` / \`task_update\` / \`task_wait\` /
-\`task_complete\` MCP tools to set the activity subheader and post
-meaningful log entries.
-
-When you launch a \`Bash\` tool with \`run_in_background: true\` (or
-any long-running shell / monitor / poll loop), call
-\`task_set_shells\` with one short description per active background
-shell — and call it again with the updated list (or \`[]\`) when one
-completes. The board flips a waiting card to **orange** while the
-list is non-empty so the user can tell at a glance the session is
-parked on background work, not stalled on them. Hooks have no way
-to enumerate the bg-task list externally, so this is on the
-assistant.
-
 ## Purpose
 
 - Inventory of servers and their state