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/aegis-logo.svg

@@ -0,0 +1,70 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512" fill="none">
+  <defs>
+    <linearGradient id="shieldGrad" x1="0" y1="0" x2="1" y2="1">
+      <stop offset="0%" stop-color="#06b6d4"/>
+      <stop offset="100%" stop-color="#0e7490"/>
+    </linearGradient>
+    <linearGradient id="innerGrad" x1="0" y1="0" x2="0" y2="1">
+      <stop offset="0%" stop-color="#22d3ee" stop-opacity="0.25"/>
+      <stop offset="100%" stop-color="#06b6d4" stop-opacity="0.05"/>
+    </linearGradient>
+    <filter id="glow">
+      <feGaussianBlur stdDeviation="6" result="blur"/>
+      <feMerge>
+        <feMergeNode in="blur"/>
+        <feMergeNode in="SourceGraphic"/>
+      </feMerge>
+    </filter>
+  </defs>
+
+  <!-- Shield body -->
+  <path
+    d="M256 28 L462 108 C462 108 472 300 256 484 C40 300 50 108 50 108 Z"
+    fill="url(#shieldGrad)"
+    stroke="#22d3ee"
+    stroke-width="6"
+    filter="url(#glow)"
+  />
+
+  <!-- Inner shield -->
+  <path
+    d="M256 64 L428 130 C428 130 436 290 256 448 C76 290 84 130 84 130 Z"
+    fill="url(#innerGrad)"
+    stroke="#22d3ee"
+    stroke-width="2"
+    stroke-opacity="0.3"
+  />
+
+  <!-- Circuit lines (left) -->
+  <g stroke="#0f172a" stroke-width="3" stroke-opacity="0.4">
+    <line x1="140" y1="200" x2="200" y2="200"/>
+    <line x1="140" y1="200" x2="140" y2="260"/>
+    <circle cx="140" cy="200" r="4" fill="#0f172a" fill-opacity="0.4"/>
+    <line x1="160" y1="280" x2="200" y2="280"/>
+    <circle cx="160" cy="280" r="4" fill="#0f172a" fill-opacity="0.4"/>
+  </g>
+
+  <!-- Circuit lines (right) -->
+  <g stroke="#0f172a" stroke-width="3" stroke-opacity="0.4">
+    <line x1="372" y1="200" x2="312" y2="200"/>
+    <line x1="372" y1="200" x2="372" y2="260"/>
+    <circle cx="372" cy="200" r="4" fill="#0f172a" fill-opacity="0.4"/>
+    <line x1="352" y1="280" x2="312" y2="280"/>
+    <circle cx="352" cy="280" r="4" fill="#0f172a" fill-opacity="0.4"/>
+  </g>
+
+  <!-- Central "A" letterform -->
+  <g filter="url(#glow)">
+    <path
+      d="M256 140 L312 320 L292 320 L278 276 L234 276 L220 320 L200 320 Z
+         M240 256 L272 256 L256 192 Z"
+      fill="#0f172a"
+      fill-opacity="0.85"
+    />
+  </g>
+
+  <!-- Lock/keyhole at bottom of A -->
+  <circle cx="256" cy="350" r="22" fill="#0f172a" fill-opacity="0.7" stroke="#22d3ee" stroke-width="2" stroke-opacity="0.5"/>
+  <circle cx="256" cy="345" r="8" fill="#22d3ee" fill-opacity="0.8"/>
+  <rect x="252" y="348" width="8" height="14" rx="2" fill="#22d3ee" fill-opacity="0.8"/>
+</svg>