feat: driver documents (sovereignty storage adapter) + load-test script

- documents: upload (multipart) + review (admin/CS) + auto-approve driver when all docs approved
- StorageService: per-tenant local volume now, in-country storage swap via STORAGE_BASE_URL
- doc.number encrypted (AES-256-GCM); migration InitDocuments; tripz-storage volume
- scripts/loadtest.mjs: concurrent full trip-cycle benchmark (throughput + latency percentiles)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/docker-compose.yml

@@ -51,6 +51,8 @@ services:
     depends_on: [postgres, redis]
     ports:
       - "${API_PORT:-4010}:4010"
+    volumes:
+      - tripz-storage:/app/storage
     networks: [tripz-net]
 
   worker:
@@ -68,6 +70,7 @@ services:
 volumes:
   tripz-pgdata:
   tripz-redisdata:
+  tripz-storage:
 
 networks:
   tripz-net: