Add VLAN management page at /vlans

- Full CRUD: create, inline-edit, delete with confirm dialog
- Table shows VLAN ID, name, description, color swatch
- Add-VLAN form at top; hover shows edit/delete actions per row
- Route registered in App.tsx under ProtectedRoute
- VLANs nav button added to RackToolbar and MapToolbar

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

client/src/components/mapper/MapToolbar.tsx

@@ -1,6 +1,6 @@
 import { useState } from 'react';
 import { useNavigate } from 'react-router-dom';
-import { Download, Server, LogOut, ChevronDown } from 'lucide-react';
+import { Download, Server, LogOut, ChevronDown, Tag } from 'lucide-react';
 import { toast } from 'sonner';
 import { toPng } from 'html-to-image';
 import { useReactFlow } from '@xyflow/react';
@@ -119,6 +119,10 @@ export function MapToolbar({
           <Server size={14} />
           Rack Planner
         </Button>
+        <Button size="sm" variant="secondary" onClick={() => navigate('/vlans')}>
+          <Tag size={14} />
+          VLANs
+        </Button>
         {activeMapId && (
           <>
             <Button size="sm" variant="secondary" onClick={onPopulate} title="Import all rack modules as nodes">