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>

scripts/consistency_check.py

@@ -15,7 +15,7 @@ Checks:
   C-08  orphan-db-completed      INFO  No   Completed/archived DB workstream, no file
   C-09  workstream-repo-mismatch FAIL  Yes  DB workstream repo_id != file location
   C-10  task-status-drift        WARN  Yes  Task status differs between file and DB
-  C-11  task-unlinked            INFO  Yes  Task block has no state_hub_task_id
+  C-11  task-unlinked            WARN  Yes  Task block has no state_hub_task_id
   C-12  orphan-db-task           WARN  No   DB task in workstream has no file backing
 
 Usage:
@@ -475,7 +475,7 @@ def check_repo(api_base: str, repo_slug: str) -> ConsistencyReport:
             elif t_id:
                 # C-11: task exists in file but not linked to DB
                 report.add(
-                    severity="INFO", check_id="C-11",
+                    severity="WARN", check_id="C-11",
                     message=f"Task '{t_id}' has no state_hub_task_id",
                     file_path=f"{fname}#{t_id}",
                     fixable=True,