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/backoffice/src/components/operations/LastMileRequestsPanel.tsx

@@ -94,6 +94,20 @@ export function LastMileRequestsPanel() {
   const invalidate = () =>
     qc.invalidateQueries({ queryKey: QUERY_KEYS.LAST_MILE_REQUESTS.ROOT });
 
+  const downloadContract = async (r: LastMileRequest) => {
+    try {
+      const { data: blob } = await lastMileRequestsService.contractDocument(r.id);
+      const url = URL.createObjectURL(blob);
+      const a = document.createElement("a");
+      a.href = url;
+      a.download = `LM_${r.booking?.company?.name?.replace(/[^A-Za-z0-9._-]+/g, "_") ?? r.id}.pdf`;
+      a.click();
+      URL.revokeObjectURL(url);
+    } catch {
+      toast({ title: "Contract PDF not available", variant: "destructive" });
+    }
+  };
+
   const approve = useMutation({
     mutationFn: () =>
       lastMileRequestsService.approve(approveTarget!.id, Number(advanceAmount)),
@@ -141,8 +155,16 @@ export function LastMileRequestsPanel() {
       id: "containers",
       header: () => <span>Requested Containers</span>,
       cell: ({ row }) => {
-        const nums = row.original.requestedContainerNumbers;
-        return <Text size="sm">{nums?.length ? nums.join(", ") : "—"}</Text>;
+        const r = row.original;
+        const nums = r.requestedContainerNumbers;
+        return (
+          <Stack gap={0}>
+            <Text size="sm">{nums?.length ? nums.join(", ") : "—"}</Text>
+            {r.requestedDeliveryDate && (
+              <Text size="xs" c="dimmed">Delivery: {r.requestedDeliveryDate}</Text>
+            )}
+          </Stack>
+        );
       },
     },
     {
@@ -162,6 +184,24 @@ export function LastMileRequestsPanel() {
         );
       },
     },
+    {
+      id: "contract",
+      header: () => <span>LM Contract</span>,
+      cell: ({ row }) => {
+        const r = row.original;
+        if (r.status !== "APPROVED") return <Text size="sm" c="dimmed">—</Text>;
+        return (
+          <Stack gap={4} align="flex-start">
+            <Badge color={r.customerSignedAt ? "green" : "yellow"} variant="light" size="sm">
+              {r.customerSignedAt ? "Signed" : "Awaiting signature"}
+            </Badge>
+            <Button size="compact-xs" variant="subtle" onClick={() => void downloadContract(r)}>
+              Download PDF
+            </Button>
+          </Stack>
+        );
+      },
+    },
     ...(canApprove
       ? [
           {