feat: transport incidents with truck number support

- DB: trucks table + incidents.truck_id FK + transport enum value
- Validation: transport type requires truck_id
- Create API: validates truck exists/active, persists truck_id
- Report form: truck dropdown shown when type=transport (required)
- Admin: TruckManager CRUD + /api/admin/trucks route
- Detail: trucks join surfaced in incident-detail + detail page query
- Inbox (HSE + supervisor): truck filter, transport in TYPE_OPTIONS,
  fixed stale enum values (dropped dangerous_occurrence/mhe_asset/occupational_disease)
- List: transport label + truck number badge in rows
- i18n: transport + truckLabel/truckPlaceholder in en/ms/zh

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CPf5Rc8QPx6V8KLEEgfKEQ

messages/en.json

@@ -16,7 +16,9 @@
     "qualityScoreLabel": "Report quality — {score}/10",
     "errorGeneric": "Something went wrong. Please try again.",
     "savedOffline": "Report saved. It will be submitted automatically when you're back online.",
-    "offlineBanner": "You're offline. Your report will be saved and submitted when you reconnect."
+    "offlineBanner": "You're offline. Your report will be saved and submitted when you reconnect.",
+    "truckLabel": "Truck",
+    "truckPlaceholder": "Select truck…"
   },
   "IncidentType": {
     "injury": "Injury / Medical",
@@ -25,7 +27,8 @@
     "asset_damage": "Asset / Equipment Damage",
     "environmental": "Environmental Incident",
     "security": "Security Incident",
-    "fire": "Fire / Emergency"
+    "fire": "Fire / Emergency",
+    "transport": "Transport / Vehicle"
   },
   "MedicalStatus": {
     "none": "No treatment needed",