feat(bookings): add ad-hoc additional-charge module

New freight.additional_charge table, independent of BookingClearanceCharge
(unbounded per booking, free-text reason). Draft -> send issues an invoice
and notifies the customer in-app/SMS/email; settles via the standard
.invoice.paid event. Adds the Additional charges row-menu entry
next to Cancel booking, permission-gated.

Not included: the Additional Payments tab UI, add-charge modal, portal pay
flow.

apps/edr-freight-api/src/migrations/3620000000000-AdditionalCharge.ts

@@ -0,0 +1,43 @@
+import { MigrationInterface, QueryRunner } from 'typeorm';
+
+/** Ad-hoc customer charges finance raises against a booking — Additional Payments tab. */
+export class AdditionalCharge3620000000000 implements MigrationInterface {
+  name = 'AdditionalCharge3620000000000';
+
+  public async up(queryRunner: QueryRunner): Promise<void> {
+    await queryRunner.query(`
+      CREATE TABLE IF NOT EXISTS "freight"."additional_charge" (
+        "id" uuid NOT NULL DEFAULT uuid_generate_v4(),
+        "created_at" timestamptz NOT NULL DEFAULT now(),
+        "updated_at" timestamptz NOT NULL DEFAULT now(),
+        "deleted_at" timestamptz,
+        "booking_id" uuid NOT NULL,
+        "reason" text NOT NULL,
+        "status" character varying(20) NOT NULL DEFAULT 'DRAFT',
+        "amount" numeric(14,2) NOT NULL,
+        "currency" character varying(8) NOT NULL,
+        "file_record_id" uuid,
+        "invoice_id" uuid,
+        "payment_reference" character varying(64),
+        "created_by_staff_id" uuid,
+        "sent_by_staff_id" uuid,
+        "sent_at" timestamptz,
+        "paid_at" timestamptz,
+        "cancelled_by_staff_id" uuid,
+        "cancelled_at" timestamptz,
+        "cancel_reason" text,
+        CONSTRAINT "pk_additional_charge" PRIMARY KEY ("id"),
+        CONSTRAINT "fk_additional_charge_booking" FOREIGN KEY ("booking_id")
+          REFERENCES "freight"."bookings"("id") ON DELETE CASCADE
+      )
+    `);
+    await queryRunner.query(`
+      CREATE INDEX IF NOT EXISTS "idx_additional_charge_booking"
+        ON "freight"."additional_charge" ("booking_id")
+    `);
+  }
+
+  public async down(queryRunner: QueryRunner): Promise<void> {
+    await queryRunner.query(`DROP TABLE IF EXISTS "freight"."additional_charge"`);
+  }
+}