feat(tasks): add needs_human intervention flag (CUST-WP-0009)

- Migration b4c5d6e7f8a9: adds needs_human (bool) + intervention_note (text) to tasks
- API: needs_human filter on GET /tasks/; 422 if flagged without note
- 3 MCP tools: flag_for_human, clear_human_flag, list_human_interventions
- Dashboard: interventions.md with amber cards and "Mark done" button
- Policy router + workstream DoD policy (workstream-dod.md)
- Workstream lifecycle docs page + workplan CUST-WP-0010
- CLAUDE.md: add step 4 (run fix-consistency after workplan writes)
- consistency_check.py: promote C-11 unlinked tasks from INFO to WARN

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

state-hub/dashboard/src/docs/workstreams.md

@@ -16,9 +16,11 @@ A horizontal bar chart showing the count of workstreams in each status for the c
 |---|---|
 | **active** | Work in progress or ready to start |
 | **blocked** | Waiting on something outside the workstream — see Dependencies |
-| **completed** | Done |
+| **completed** | Formally accepted after custodian review (shown as **accepted** in the overview chart) |
 | **archived** | Closed without completion; no longer relevant |
 
+See [Workstream Lifecycle](/docs/workstream-lifecycle) for the full state model including derived states (finished, stalled, oldies).
+
 ---
 
 ## Filter bar