feat: Phase 5 & 6 — usability, compliance hardening, analytics

Phase 5 (usability + compliance):
- In-app notification bell/badge: migration 016 adds read state + per-user
  RLS + create_in_app_notification SECURITY DEFINER RPC; /api/notifications;
  wired into incident creation, CAPA assign/verify, escalation cron
- Incident closure: new POST /api/incidents/[id]/close (requires verification
  status + all CAPAs verified); migration 017 locks closed incidents at DB
  level (update/delete triggers) with append-only incident_addenda + UI panel
- Server-side pagination on HSE/supervisor incident inboxes (.range, 25/page)
- Investigation form: alcohol/urine test result + witness statement refs
  (existing schema columns, now editable)
- Type-specific intake fields: migration 018 adds incidents.type_details
  JSONB; whitelist validation; environmental/asset/security/fire field
  groups in report form; EN/MS/ZH labels; offline queue support
- JKKP 8 annual register CSV export (/api/reports/jkkp8) + dashboard button
  + January statutory deadline banner
- Admin page: user invite (service-role client), role/site/active management,
  site + zone CRUD with QR report links — replaces Phase 0 stub
- Evidence gallery thumbnails via Supabase render transform with fallback

Phase 6 (analytics):
- 12-month stacked trend chart (leading/lagging/other) + top root causes
  (lib/dashboard/trends.ts pure helpers)
- AI rising-risk zones: /api/dashboard/ai/risk-flags aggregates 90-day
  zone stats, claude-opus-4-8 forced tool_use, panel on HSE + management
  dashboards, suggestion audit-logged

Also fixes 9 pre-existing missing /ims basePath prefixes in client fetches
and download links.

132 tests passing, tsc clean, next build clean.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CPf5Rc8QPx6V8KLEEgfKEQ

app/api/incidents/[id]/investigation/route.ts

@@ -37,6 +37,8 @@ export async function POST(
       root_cause_summary: body.root_cause_summary ?? null,
       five_why_steps: method === 'five_why' ? (body.five_why_steps ?? []) : null,
       fishbone_categories: method === 'fishbone' ? (body.fishbone_categories ?? []) : null,
+      alcohol_test_result: body.alcohol_test_result ?? null,
+      witness_statement_refs: Array.isArray(body.witness_statement_refs) ? body.witness_statement_refs : [],
     })
     .select('id')
     .single()
@@ -83,6 +85,8 @@ export async function PATCH(
     root_cause_summary: fields.root_cause_summary ?? null,
     five_why_steps: fields.five_why_steps ?? null,
     fishbone_categories: fields.fishbone_categories ?? null,
+    alcohol_test_result: fields.alcohol_test_result ?? null,
+    witness_statement_refs: Array.isArray(fields.witness_statement_refs) ? fields.witness_statement_refs : [],
   }
   if (complete) updateData.completed_at = new Date().toISOString()