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>

api/models/task.py

@@ -2,7 +2,7 @@ import enum
 import uuid
 from datetime import date
 
-from sqlalchemy import Date, Enum, ForeignKey, String, Text
+from sqlalchemy import Boolean, Date, Enum, ForeignKey, String, Text
 from sqlalchemy.dialects.postgresql import UUID
 from sqlalchemy.orm import Mapped, mapped_column, relationship
 
@@ -44,6 +44,8 @@ class Task(Base, TimestampMixin):
     assignee: Mapped[str | None] = mapped_column(String(100), nullable=True)
     due_date: Mapped[date | None] = mapped_column(Date, nullable=True)
     blocking_reason: Mapped[str | None] = mapped_column(Text, nullable=True)
+    needs_human: Mapped[bool] = mapped_column(Boolean, default=False, nullable=False, index=True)
+    intervention_note: Mapped[str | None] = mapped_column(Text, nullable=True)
     parent_task_id: Mapped[uuid.UUID | None] = mapped_column(
         UUID(as_uuid=True), ForeignKey("tasks.id", ondelete="SET NULL"), nullable=True
     )