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>

mcp_server/server.py

@@ -321,6 +321,71 @@ def update_task_status(
     return json.dumps(task, indent=2)
 
 
+@mcp.tool()
+def flag_for_human(task_id: str, note: str) -> str:
+    """Flag a task as requiring human intervention.
+
+    Sets needs_human=True and records the required action as intervention_note.
+    Emits a progress event so the flag is visible in session history.
+
+    Args:
+        task_id: UUID of the task to flag
+        note: description of the action required from the human (required)
+    """
+    task = _patch(f"/tasks/{task_id}", {
+        "needs_human": True,
+        "intervention_note": note,
+    })
+    _post("/progress", {
+        "task_id": task_id,
+        "workstream_id": task.get("workstream_id"),
+        "event_type": "task_flagged_human",
+        "summary": f"Task flagged for human intervention: {task['title']}",
+        "author": "custodian",
+        "detail": {"intervention_note": note},
+    })
+    return json.dumps(task, indent=2)
+
+
+@mcp.tool()
+def clear_human_flag(task_id: str) -> str:
+    """Clear the human-intervention flag from a task.
+
+    Sets needs_human=False. The intervention_note is preserved as a
+    historical record. Call this after the human has completed the action.
+
+    Args:
+        task_id: UUID of the task to clear
+    """
+    task = _patch(f"/tasks/{task_id}", {
+        "needs_human": False,
+    })
+    _post("/progress", {
+        "task_id": task_id,
+        "workstream_id": task.get("workstream_id"),
+        "event_type": "task_flag_cleared",
+        "summary": f"Human-intervention flag cleared: {task['title']}",
+        "author": "custodian",
+    })
+    return json.dumps(task, indent=2)
+
+
+@mcp.tool()
+def list_human_interventions(workstream_id: str | None = None) -> str:
+    """List all tasks flagged for human intervention.
+
+    Returns tasks where needs_human=True, optionally filtered to one workstream.
+    Use this at session start to surface Bernd's action items.
+
+    Args:
+        workstream_id: optional UUID to scope results to one workstream
+    """
+    return json.dumps(
+        _get("/tasks", {"needs_human": "true", "workstream_id": workstream_id}),
+        indent=2,
+    )
+
+
 @mcp.tool()
 def record_decision(
     title: str,