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/src/database/migrations/1721700000000-InitDocuments.ts

@@ -0,0 +1,28 @@
+import { MigrationInterface, QueryRunner } from 'typeorm';
+
+/** وثائق السائق. الجدول: tripz_driver_documents. */
+export class InitDocuments1721700000000 implements MigrationInterface {
+  public async up(q: QueryRunner): Promise<void> {
+    await q.query(`
+      CREATE TABLE IF NOT EXISTS tripz_driver_documents (
+        id uuid PRIMARY KEY DEFAULT uuid_generate_v4(),
+        tenant_id uuid NOT NULL,
+        driver_id uuid NOT NULL,
+        type varchar NOT NULL,
+        file_key varchar NOT NULL,
+        number varchar,
+        expiry_date date,
+        status varchar NOT NULL DEFAULT 'pending',
+        review_note varchar,
+        reviewed_by uuid,
+        created_at timestamptz NOT NULL DEFAULT now(),
+        updated_at timestamptz NOT NULL DEFAULT now()
+      )`);
+    await q.query(`CREATE INDEX IF NOT EXISTS "IDX_tripz_driver_documents_driver" ON tripz_driver_documents (tenant_id, driver_id)`);
+    await q.query(`CREATE INDEX IF NOT EXISTS "IDX_tripz_driver_documents_status" ON tripz_driver_documents (tenant_id, status)`);
+  }
+
+  public async down(q: QueryRunner): Promise<void> {
+    await q.query(`DROP TABLE IF EXISTS tripz_driver_documents`);
+  }
+}