Settings: Dotfiles file-browser workspace

- New Settings → Dotfiles section: a mini-workspace rooted at home/{firstName}
  reusing FileTree + the Monaco CodeEditor
- Drag-and-drop files/folders (FileSystem entries API) or upload a folder
  (webkitdirectory) / files; edit in-place; new file; delete
- Files stored relative to HOME via the encrypted userDotfiles API
- Repo & setup panel (public repo URL + ref + setup script path) writing
  userEnvironment; secrets nudge toward the Secrets feature

apps/next/src/app/(app)/settings/layout.tsx

@@ -3,7 +3,7 @@
 import type { ReactNode } from 'react';
 import Link from 'next/link';
 import { usePathname } from 'next/navigation';
-import { Brain, Github, ServerCog, Shield, User } from 'lucide-react';
+import { Brain, FileCog, Github, ServerCog, Shield, User } from 'lucide-react';
 
 import { cn } from '@spoon/ui';
 
@@ -11,6 +11,7 @@ const settingsItems = [
   { href: '/settings/profile', label: 'Profile', icon: User },
   { href: '/settings/integrations', label: 'Integrations', icon: Github },
   { href: '/settings/ai-providers', label: 'AI providers', icon: Brain },
+  { href: '/settings/dotfiles', label: 'Dotfiles', icon: FileCog },
   { href: '/settings/worker', label: 'Worker', icon: ServerCog },
   { href: '/settings/security', label: 'Security', icon: Shield },
 ];