feat: Add Wild Central web app (Central-only UI)

Extract Central pages from the wild-cloud web app into a standalone
React app for Wild Central. Includes:

- Central overview, DNS, DHCP, Firewall, VPN, Ingress, CrowdSec pages
- Simplified sidebar with Central-only navigation
- Branding updated to "Wild Central"
- All Cloud-specific pages, components, hooks, and API services removed
- TypeScript type-check and production build pass

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

web/src/components/ThemeToggle.tsx

@@ -0,0 +1,52 @@
+import { Moon, Sun, Monitor } from 'lucide-react';
+import { Button } from './ui/button';
+import { useTheme } from '../contexts/ThemeContext';
+
+export function ThemeToggle() {
+  const { theme, setTheme } = useTheme();
+
+  const cycleTheme = () => {
+    if (theme === 'light') {
+      setTheme('dark');
+    } else if (theme === 'dark') {
+      setTheme('system');
+    } else {
+      setTheme('light');
+    }
+  };
+
+  const getIcon = () => {
+    switch (theme) {
+      case 'light':
+        return <Sun className="h-4 w-4" />;
+      case 'dark':
+        return <Moon className="h-4 w-4" />;
+      default:
+        return <Monitor className="h-4 w-4" />;
+    }
+  };
+
+  const getLabel = () => {
+    switch (theme) {
+      case 'light':
+        return 'Light mode';
+      case 'dark':
+        return 'Dark mode';
+      default:
+        return 'System theme';
+    }
+  };
+
+  return (
+    <Button
+      variant="ghost"
+      size="sm"
+      onClick={cycleTheme}
+      title={`Current: ${getLabel()}. Click to cycle themes.`}
+      className="gap-2"
+    >
+      {getIcon()}
+      <span className="text-xs font-medium">{getLabel()}</span>
+    </Button>
+  );
+}