Add API Q1 CAPA: root cause, corrective action gate, effectiveness verification

Implements tester feedback against API Q1 §5.9.1.2 / §6.4.2:

- Root Cause field + 6M Root Cause Category lookup (Man/Machine/Method/
  Material/Measurement/Environment), separate from Deviation Detail/Category
- "Corrective Action Required?" Yes/No gate on every NCR with a required
  justification
- Corrective action plan with owner + due date; owner is notified by email
- Effectiveness verification (result, notes, server-stamped verifier/date)
  required before an NCR can close when corrective action is required —
  costing returns 409 listing the missing pieces
- Recurring-issue flag with bidirectional NCR-to-NCR links; prior NCRs show
  a warning when later NCRs reference them
- Dashboard metrics: % root cause completed, % CAPA verified effective,
  avg CAPA close time, overdue CAPA count, NCRs by root cause category
- CAPA section in the NCR detail UI, printable PDF, CSV export, and the
  vw_ncr_full Power BI view; admin list manager for root cause categories
- Migrations 0003 (schema + seeded 6M lookup) and 0004 (view refresh);
  demo seed data exercises every metric

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

backend/tests/util.py

@@ -92,8 +92,23 @@ async def to_costing(client: AsyncClient, team: dict, ncr_id: int) -> dict:
     return r.json()["ncr"]
 
 
+async def answer_capa_no(client: AsyncClient, team: dict, ncr_id: int) -> dict:
+    """Answer the API Q1 corrective-action gate with 'No' so the NCR can close."""
+    r = await client.post(
+        f"/api/ncrs/{ncr_id}/capa",
+        json={
+            "corrective_action_required": False,
+            "corrective_action_justification": "Isolated incident; contained by disposition.",
+        },
+        headers=hdr(team["qc"]),
+    )
+    assert r.status_code == 200, r.text
+    return r.json()["ncr"]
+
+
 async def to_closed(client: AsyncClient, team: dict, ncr_id: int) -> dict:
     await to_costing(client, team, ncr_id)
+    await answer_capa_no(client, team, ncr_id)
     r = await client.post(
         f"/api/ncrs/{ncr_id}/costing",
         json={