feat(web/attackers): surface ASN + AS name on cards and detail

Attacker list cards gain an AS<number> chip with the AS description
on hover. Attacker detail page adds an AS row beside ORIGIN — same
shape as the existing country/source pair so operators can read
"this attacker is in DE on AS24940 Hetzner" at a glance instead of
having to grep the IP into a separate tool.

Both fields collapse to "unknown" when the IP isn't BGP-announced
(CGNAT, dark space, RFC1918), matching the existing pattern for
country resolution.

decnet_web/src/components/Attackers.css

@@ -92,6 +92,16 @@
   font-size: 0.72rem;
   opacity: 0.7;
 }
+.attackers-root .ak-card .ak-asn {
+  font-size: 0.62rem;
+  letter-spacing: 1px;
+  padding: 1px 6px;
+  border: 1px solid var(--border);
+  color: var(--matrix);
+  opacity: 0.75;
+  font-weight: 600;
+  cursor: help;
+}
 
 .attackers-root .ak-stats {
   display: flex;