CLAUDE.md: assistants must call task_set_shells on bg-bash launches

The task-board v0.1.11 orange-while-waiting treatment depends on the
assistant pushing the pending-shells list — hooks can't enumerate
Claude Code's background tasks externally (confirmed against the
hook docs: no payload field, no state file, no lifecycle event, no
JSON form of /tasks). So the discipline lives in CLAUDE.md.

CLAUDE.md

@@ -20,6 +20,15 @@ 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