fix(documents-hub): scope gradient PageHeader to root view; add inline New-document button on folder views

The gradient "Documents — Track signing status..." banner was rendering on
all three render modes (HubRootView / EntityFolderView / FlatFolderListing),
duplicating the in-empty-state CTA on folder views. Keep it only on the
root landing page; for folder views, surface a compact "+ New document"
button in the upper-right aligned with the FolderBreadcrumb row.

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

src/components/documents/documents-hub.tsx

@@ -151,8 +151,20 @@ export function DocumentsHub({ portSlug }: DocumentsHubProps) {
         }
       />
       <div className="flex-1 min-w-0 p-4 space-y-4">
+        <div className="flex items-center justify-between gap-3">
           <FolderBreadcrumb selectedFolderId={selectedFolderId} onSelect={handleFolderSelect} />
+          {selectedFolderId !== undefined && (
+            <Button asChild size="sm">
+              <Link href={`/${portSlug}/documents/new`}>
+                <Plus className="mr-1.5 h-4 w-4" />
+                New document
+              </Link>
+            </Button>
+          )}
+        </div>
 
+        {selectedFolderId === undefined ? (
+          <>
             <PageHeader
               title="Documents"
               description="Track signing status, chase pending signers, and audit completion."
@@ -166,9 +178,8 @@ export function DocumentsHub({ portSlug }: DocumentsHubProps) {
               }
               variant="gradient"
             />
-
-        {selectedFolderId === undefined ? (
             <HubRootView portSlug={portSlug} />
+          </>
         ) : isEntityFolder && isEntityType(folderEntityType) ? (
           <EntityFolderView
             portSlug={portSlug}