feat(freight): record when a company is approved

Ticket #420 — add approved_at to companies (migration), stamped at
both promotion sites (first-profile auto-approve and manual staff
status change). Surfaced as Submitted on/Approved on in the backoffice
customer list and detail views.

apps/edr-freight-api/src/migrations/3120000000000-AddApprovedAtToCompanies.ts

@@ -0,0 +1,24 @@
+import { MigrationInterface, QueryRunner } from "typeorm";
+
+/**
+ * Pending→Active is the only company-level approval event; `updatedAt` can't
+ * stand in for it since any field edit bumps that too. Nullable — existing
+ * companies (approved before this column existed) have no recorded moment.
+ */
+export class AddApprovedAtToCompanies3120000000000 implements MigrationInterface {
+  name = "AddApprovedAtToCompanies3120000000000";
+
+  public async up(queryRunner: QueryRunner): Promise<void> {
+    await queryRunner.query(
+      `ALTER TABLE freight.companies
+         ADD COLUMN IF NOT EXISTS approved_at timestamptz`,
+    );
+  }
+
+  public async down(queryRunner: QueryRunner): Promise<void> {
+    await queryRunner.query(
+      `ALTER TABLE freight.companies
+        DROP COLUMN IF EXISTS approved_at`,
+    );
+  }
+}