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/components/Sidebar.tsx

@@ -119,6 +119,7 @@ const Sidebar: React.FC<SidebarProps> = ({ business, user, isCollapsed, toggleCo
             icon={Clock}
             label={t('nav.tasks', 'Tasks')}
             isCollapsed={isCollapsed}
+            locked={!canUse('plugins') || !canUse('tasks')}
           />
         </SidebarSection>
 
@@ -193,7 +194,7 @@ const Sidebar: React.FC<SidebarProps> = ({ business, user, isCollapsed, toggleCo
         {canViewAdminPages && (
           <SidebarSection title={t('nav.sections.extend', 'Extend')} isCollapsed={isCollapsed}>
             <SidebarItem
-              to="/plugins/marketplace"
+              to="/plugins/my-plugins"
               icon={Plug}
               label={t('nav.plugins', 'Plugins')}
               isCollapsed={isCollapsed}