feat(web): live detail tree, server map, favicon

dns.squish.net-style traversal detail tree (refid-parented via longest
prefix, collapsible .0 resolve subtrees, completed-earlier markers, raw
log fallback), a servers card with Leaflet/OSM map lazy-loaded from CDN
and client-side geojs.io geolocation with graceful degradation, and a
delegation-tree favicon (ico + svg).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

web/api/static/favicon.svg

@@ -0,0 +1,13 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 32 32">
+  <!-- ExploreDNS: delegation tree — root fanning to leaves, green = answered path -->
+  <rect width="32" height="32" rx="5.8" fill="#2563eb"/>
+  <g stroke="#ffffff" stroke-width="1.8" stroke-linecap="round">
+    <line x1="16" y1="7" x2="7" y2="24"/>
+    <line x1="16" y1="7" x2="16" y2="25"/>
+    <line x1="16" y1="7" x2="25" y2="24"/>
+  </g>
+  <circle cx="16" cy="7" r="3.5" fill="#ffffff"/>
+  <circle cx="7" cy="24" r="2.9" fill="#ffffff"/>
+  <circle cx="16" cy="25" r="2.9" fill="#4ade80"/>
+  <circle cx="25" cy="24" r="2.9" fill="#ffffff"/>
+</svg>