feat(last-mile): customer-signed LM contract gates the advance invoice

Approval now snapshots the rate estimate and generates a last-mile
contract instead of invoicing immediately. The customer picks a delivery
date on the confirm form, then reviews and signs the contract in the
portal (saved signature or drawn); the signed PDF is stored as
LM_<CustomerName>.pdf and only then is the advance invoice issued.
Backoffice shows signature status and the contract download.

apps/edr-freight-web/portal/src/services/last-mile-requests.service.ts

@@ -10,11 +10,35 @@ export interface LastMileRequest {
   trainScheduleId: string;
   status: "AWAITING_CONFIRMATION" | "SUBMITTED" | "APPROVED" | "REJECTED";
   requestedContainerNumbers?: string[] | null;
+  requestedDeliveryDate?: string | null;
+  customerSignedAt?: string | null;
   rejectionReason?: string | null;
   createdAt: string;
   updatedAt: string;
 }
 
+export interface LastMileContractView {
+  requestId: string;
+  bookingId: string;
+  bookingReference?: string | null;
+  status: LastMileRequest["status"];
+  html: string;
+  customerSignedAt: string | null;
+  signerDisplayName: string | null;
+  canSign: boolean;
+  savedSignature?: {
+    signerDisplayName: string;
+    signatureImageUrl: string | null;
+    stampImageUrl: string | null;
+  };
+}
+
+export interface SignLastMileContractPayload {
+  signatureImageBase64?: string;
+  signerDisplayName: string;
+  consentText?: string;
+}
+
 export const lastMileRequestsService = {
   /** One last-mile confirmation request, by id. */
   get: async (id: string): Promise<LastMileRequest> => {
@@ -22,12 +46,36 @@ export const lastMileRequestsService = {
     return data.data ?? data;
   },
 
-  /** Confirm which containers on the booking go via EDR last-mile. */
+  /** Confirm which containers go via EDR last-mile and the requested delivery date. */
   submit: async (
     id: string,
     containerNumbers: string[],
+    deliveryDate: string,
   ): Promise<LastMileRequest> => {
-    const { data } = await client.post(L.SUBMIT(id), { containerNumbers });
+    const { data } = await client.post(L.SUBMIT(id), { containerNumbers, deliveryDate });
     return data.data ?? data;
   },
+
+  /** LM contract view model + rendered HTML + saved signature. */
+  getContractView: async (id: string): Promise<LastMileContractView> => {
+    const { data } = await client.get(L.CONTRACT_VIEW(id));
+    return data.data ?? data;
+  },
+
+  /** Agree & sign the LM contract — the advance invoice is issued right after. */
+  signContract: async (
+    id: string,
+    payload: SignLastMileContractPayload,
+  ): Promise<LastMileRequest> => {
+    const { data } = await client.post(L.CONTRACT_SIGN(id), payload);
+    return data.data ?? data;
+  },
+
+  /** The LM contract PDF (LM_<CustomerName>.pdf). */
+  downloadContractDocument: async (id: string): Promise<Blob> => {
+    const { data } = await client.get(L.CONTRACT_DOCUMENT(id), {
+      responseType: "blob",
+    });
+    return data;
+  },
 };