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/app/schemas/report.py

@@ -44,6 +44,12 @@ class ReportsSummaryOut(BaseModel):
     open_ncrs: int
     closed_ncrs: int
     total_cost: Decimal
+    # ── CAPA metrics (API Q1 §6.4.2) ─────────────────────────────────────────
+    root_cause_pct: float | None  # % of NCRs with a completed root cause
+    effectiveness_verified_pct: float | None  # % of CA-required NCRs verified effective
+    avg_capa_close_days: float | None  # CA opened → verified effective
+    overdue_capa_count: int  # CA required, past due, not yet verified effective
+    by_root_cause_category: list[CountByName]
     by_department: list[CountByName]
     by_category: list[CountByName]
     by_month: list[CountByMonth]