feat: Dashboard redesign, plan permissions, and help docs improvements

Major updates including:
- Customizable dashboard with drag-and-drop widget grid layout
- Plan-based feature locking for plugins and tasks
- Comprehensive help documentation updates across all pages
- Plugin seeding in deployment process for all tenants
- Permission synchronization system for subscription plans
- QuotaOverageModal component and enhanced UX flows

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

frontend/src/pages/HelpGuide.tsx

@@ -77,9 +77,7 @@ const HelpGuide: React.FC = () => {
       title: 'Extend',
       description: 'Add functionality with plugins',
       links: [
-        { label: 'Plugins Overview', path: '/help/plugins', icon: <Puzzle size={18} /> },
-        { label: 'Creating Plugins', path: '/help/plugins/create', icon: <Puzzle size={18} /> },
-        { label: 'Plugin Documentation', path: '/help/plugins/docs', icon: <BookOpen size={18} /> },
+        { label: 'Plugins', path: '/help/plugins', icon: <Puzzle size={18} /> },
       ],
     },
     {