feat(documents): rebuild hub — root view + entity-folder view

Three rendering modes for the main panel:
  - HubRootView (no folder selected): port-wide Signing + recent Files.
  - EntityFolderView (system-managed entity subfolder selected):
    AggregatedSection × 2 with owner-grouped subsections + per-row
    "view signing details" link on signed files (heuristic: filename
    starts with "signed-"; follow-up: surface signedFromDocumentId
    from the aggregated API).
  - FlatFolderListing (any other folder): existing search + chips + list.

Drops the signing-status tab strip (in_progress / awaiting_them / etc.)
— folders are the primary navigation now. hub-counts query removed.

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

src/components/documents/hub-root-view.tsx

@@ -0,0 +1,87 @@
+'use client';
+
+import Link from 'next/link';
+import { FileText, ClipboardSignature } from 'lucide-react';
+
+import { usePaginatedQuery } from '@/hooks/use-paginated-query';
+
+interface HubRootDoc {
+  id: string;
+  title: string;
+  documentType: string;
+  status: string;
+  createdAt: string;
+}
+
+interface HubRootFile {
+  id: string;
+  filename: string;
+  createdAt: string;
+}
+
+interface Props {
+  portSlug: string;
+}
+
+export function HubRootView({ portSlug }: Props) {
+  const { data: workflows, isLoading: workflowsLoading } = usePaginatedQuery<HubRootDoc>({
+    queryKey: ['documents', 'hub-root', 'workflows'],
+    endpoint: '/api/v1/documents?tab=in_progress',
+    filterDefinitions: [],
+  });
+  const { data: filesData, isLoading: filesLoading } = usePaginatedQuery<HubRootFile>({
+    queryKey: ['files', 'hub-root'],
+    endpoint: '/api/v1/files?sort=createdAt&order=desc&limit=20',
+    filterDefinitions: [],
+  });
+
+  return (
+    <div className="space-y-4">
+      <section className="rounded-md border bg-white">
+        <h3 className="flex items-center gap-2 border-b px-3 py-2 text-sm font-semibold">
+          <ClipboardSignature className="h-4 w-4 text-muted-foreground" />
+          Signing in progress
+        </h3>
+        {workflowsLoading ? (
+          <div className="p-3 text-sm text-muted-foreground">Loading...</div>
+        ) : workflows.length === 0 ? (
+          <div className="p-3 text-sm text-muted-foreground">No workflows in flight.</div>
+        ) : (
+          <ul className="divide-y">
+            {workflows.map((w) => (
+              <li key={w.id} className="px-3 py-2 text-sm">
+                <Link href={`/${portSlug}/documents/${w.id}`} className="hover:underline">
+                  {w.title}
+                </Link>
+                <span className="ml-2 text-xs text-muted-foreground">{w.status}</span>
+              </li>
+            ))}
+          </ul>
+        )}
+      </section>
+
+      <section className="rounded-md border bg-white">
+        <h3 className="flex items-center gap-2 border-b px-3 py-2 text-sm font-semibold">
+          <FileText className="h-4 w-4 text-muted-foreground" />
+          Recent files
+        </h3>
+        {filesLoading ? (
+          <div className="p-3 text-sm text-muted-foreground">Loading...</div>
+        ) : filesData.length === 0 ? (
+          <div className="p-3 text-sm text-muted-foreground">No files yet.</div>
+        ) : (
+          <ul className="divide-y">
+            {filesData.map((f) => (
+              <li key={f.id} className="flex items-center justify-between px-3 py-2 text-sm">
+                <span className="truncate">{f.filename}</span>
+                <span className="text-xs text-muted-foreground tabular-nums">
+                  {new Date(f.createdAt).toLocaleDateString('en-GB')}
+                </span>
+              </li>
+            ))}
+          </ul>
+        )}
+      </section>
+    </div>
+  );
+}