fix: D3FEND ontology-based import, template management UX, and branding

- Rewrite D3FEND import to use tactic-level APIs for reliable technique
  fetching with proper ontology IRIs, descriptions, and tactic assignments
- Fix D3FEND technique URLs to use canonical IRI (no more 404s)
- All 255 D3FEND techniques now have descriptions from the official API
- Change Deactivate button color to red in template management table
- Add custom Aegis logo and favicon replacing default Vite assets
- Remove unused old API parsing code and clean up fallback list

frontend/src/pages/SystemPage.tsx

@@ -516,7 +516,7 @@ export default function SystemPage() {
                         disabled={toggleActiveMutation.isPending}
                         className={`flex items-center gap-1 text-xs font-medium transition-colors ${
                           tpl.is_active
-                            ? "text-yellow-400 hover:text-yellow-300"
+                            ? "text-red-400 hover:text-red-300"
                             : "text-green-400 hover:text-green-300"
                         }`}
                         title={tpl.is_active ? "Deactivate" : "Activate"}