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/public/favicon.svg

@@ -0,0 +1,18 @@
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+  <defs>
+    <linearGradient id="sg" x1="0" y1="0" x2="1" y2="1">
+      <stop offset="0%" stop-color="#06b6d4"/>
+      <stop offset="100%" stop-color="#0e7490"/>
+    </linearGradient>
+  </defs>
+  <!-- Shield -->
+  <path d="M32 3 L58 13 C58 13 60 38 32 61 C4 38 6 13 6 13 Z" fill="url(#sg)" stroke="#22d3ee" stroke-width="1.5"/>
+  <!-- Inner fill -->
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+  <!-- A letter -->
+  <path d="M32 16 L41 42 L37 42 L35 35 L29 35 L27 42 L23 42 Z M30 32 L34 32 L32 23 Z" fill="#0f172a" fill-opacity="0.9"/>
+  <!-- Lock dot -->
+  <circle cx="32" cy="46" r="3" fill="#0f172a" fill-opacity="0.7" stroke="#22d3ee" stroke-width="0.5"/>
+  <circle cx="32" cy="45.5" r="1.2" fill="#22d3ee"/>
+  <rect x="31.2" y="46" width="1.6" height="2.5" rx="0.5" fill="#22d3ee"/>
+</svg>