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

@@ -151,24 +151,35 @@ export function DocumentsHub({ portSlug }: DocumentsHubProps) {
         }
       />
       <div className="flex-1 min-w-0 p-4 space-y-4">
-        <FolderBreadcrumb selectedFolderId={selectedFolderId} onSelect={handleFolderSelect} />
-
-        <PageHeader
-          title="Documents"
-          description="Track signing status, chase pending signers, and audit completion."
-          actions={
-            <Button asChild>
+        <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>
-          }
-          variant="gradient"
-        />
+          )}
+        </div>
 
         {selectedFolderId === undefined ? (
-          <HubRootView portSlug={portSlug} />
+          <>
+            <PageHeader
+              title="Documents"
+              description="Track signing status, chase pending signers, and audit completion."
+              actions={
+                <Button asChild>
+                  <Link href={`/${portSlug}/documents/new`}>
+                    <Plus className="mr-1.5 h-4 w-4" />
+                    New document
+                  </Link>
+                </Button>
+              }
+              variant="gradient"
+            />
+            <HubRootView portSlug={portSlug} />
+          </>
         ) : isEntityFolder && isEntityType(folderEntityType) ? (
           <EntityFolderView
             portSlug={portSlug}