feat(documents): SigningDetailsDialog

Modal rendering workflow + signers + events for a signed-PDF file.
Wired to GET /api/v1/documents/[id]/signing-details. The "view signing
details" link on signed-file rows in the Files section opens this
dialog (wiring in the entity-folder view task).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/components/documents/signing-details-dialog.tsx

@@ -0,0 +1,162 @@
+'use client';
+
+import { useQuery } from '@tanstack/react-query';
+import { Loader2 } from 'lucide-react';
+
+import { apiFetch } from '@/lib/api/client';
+import {
+  Dialog,
+  DialogContent,
+  DialogDescription,
+  DialogHeader,
+  DialogTitle,
+} from '@/components/ui/dialog';
+import { StatusPill, type StatusPillStatus } from '@/components/ui/status-pill';
+
+interface SigningDetailsResponse {
+  data: {
+    workflow: {
+      id: string;
+      title: string;
+      status: string;
+      documentType: string;
+      createdAt: string;
+      updatedAt: string;
+    };
+    signers: Array<{
+      id: string;
+      signerName: string;
+      signerEmail: string;
+      signerRole: string;
+      status: string;
+      signedAt: string | null;
+    }>;
+    events: Array<{
+      id: string;
+      eventType: string;
+      createdAt: string;
+    }>;
+  };
+}
+
+interface Props {
+  documentId: string | null;
+  open: boolean;
+  onOpenChange: (open: boolean) => void;
+}
+
+export function SigningDetailsDialog({ documentId, open, onOpenChange }: Props) {
+  const { data, isLoading } = useQuery<SigningDetailsResponse>({
+    queryKey: ['document-signing-details', documentId],
+    queryFn: () =>
+      apiFetch<SigningDetailsResponse>(`/api/v1/documents/${documentId}/signing-details`),
+    enabled: Boolean(documentId) && open,
+  });
+
+  return (
+    <Dialog open={open} onOpenChange={onOpenChange}>
+      <DialogContent className="max-w-2xl">
+        <DialogHeader>
+          <DialogTitle>Signing details</DialogTitle>
+          <DialogDescription>
+            Audit trail for this signed document — signers and timeline.
+          </DialogDescription>
+        </DialogHeader>
+        {isLoading || !data ? (
+          <div className="flex items-center justify-center py-12 text-muted-foreground">
+            <Loader2 className="mr-2 h-4 w-4 animate-spin" />
+            Loading…
+          </div>
+        ) : (
+          <div className="space-y-4">
+            <section>
+              <h4 className="mb-1 text-sm font-semibold">{data.data.workflow.title}</h4>
+              <p className="flex items-center gap-2 text-xs text-muted-foreground">
+                <span>Status:</span>
+                <StatusPill status={mapWorkflowStatus(data.data.workflow.status)}>
+                  {data.data.workflow.status}
+                </StatusPill>
+                <span>·</span>
+                <span>
+                  Created {new Date(data.data.workflow.createdAt).toLocaleString('en-GB')}
+                </span>
+              </p>
+            </section>
+
+            <section>
+              <h5 className="mb-1 text-xs font-semibold uppercase tracking-wide text-muted-foreground">
+                Signers
+              </h5>
+              <ul className="divide-y rounded border bg-muted/30">
+                {data.data.signers.map((s) => (
+                  <li
+                    key={s.id}
+                    className="flex items-center justify-between gap-2 px-3 py-2 text-xs"
+                  >
+                    <div className="min-w-0">
+                      <span className="font-medium">{s.signerName}</span>
+                      <span className="ml-2 text-muted-foreground">{s.signerEmail}</span>
+                    </div>
+                    <div className="flex items-center gap-2">
+                      {s.signedAt ? (
+                        <span className="tabular-nums text-muted-foreground">
+                          {new Date(s.signedAt).toLocaleDateString('en-GB')}
+                        </span>
+                      ) : null}
+                      <StatusPill status={mapSignerStatus(s.status)}>{s.status}</StatusPill>
+                    </div>
+                  </li>
+                ))}
+              </ul>
+            </section>
+
+            <section>
+              <h5 className="mb-1 text-xs font-semibold uppercase tracking-wide text-muted-foreground">
+                Timeline
+              </h5>
+              <ol className="space-y-1 text-xs">
+                {data.data.events.map((e) => (
+                  <li key={e.id} className="flex items-center gap-2 text-muted-foreground">
+                    <span className="tabular-nums">
+                      {new Date(e.createdAt).toLocaleString('en-GB')}
+                    </span>
+                    <span>{e.eventType.replace(/_/g, ' ')}</span>
+                  </li>
+                ))}
+              </ol>
+            </section>
+          </div>
+        )}
+      </DialogContent>
+    </Dialog>
+  );
+}
+
+function mapSignerStatus(status: string): StatusPillStatus {
+  const known: Record<string, StatusPillStatus> = {
+    pending: 'pending',
+    sent: 'sent',
+    signed: 'signed',
+    declined: 'declined',
+    expired: 'expired',
+    cancelled: 'cancelled',
+    rejected: 'rejected',
+  };
+  return known[status] ?? 'pending';
+}
+
+function mapWorkflowStatus(status: string): StatusPillStatus {
+  const known: Record<string, StatusPillStatus> = {
+    pending: 'pending',
+    draft: 'draft',
+    sent: 'sent',
+    partial: 'partial',
+    completed: 'completed',
+    signed: 'signed',
+    expired: 'expired',
+    cancelled: 'cancelled',
+    declined: 'declined',
+    rejected: 'rejected',
+  };
+  return known[status] ?? 'pending';
+}