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/AttackerDetail.tsx

@@ -61,6 +61,9 @@ interface AttackerData {
   commands: { service: string; decky: string; command: string; timestamp: string }[];
   country_code: string | null;
   country_source: string | null;
+  asn: number | null;
+  as_name: string | null;
+  asn_source: string | null;
   ptr_record: string | null;
   updated_at: string;
   behavior: AttackerBehavior | null;
@@ -1262,6 +1265,26 @@ const AttackerDetail: React.FC = () => {
               <span className="dim">unknown</span>
             )}
           </div>
+          <div>
+            <span className="dim">AS: </span>
+            {attacker.asn != null ? (
+              <span className="matrix-text">
+                AS{attacker.asn}
+                {attacker.as_name && (
+                  <span className="dim" style={{ marginLeft: 6, fontSize: '0.75rem' }}>
+                    {attacker.as_name}
+                  </span>
+                )}
+                {attacker.asn_source && (
+                  <span className="dim" style={{ marginLeft: 6, fontSize: '0.75rem' }}>
+                    ({attacker.asn_source})
+                  </span>
+                )}
+              </span>
+            ) : (
+              <span className="dim">unknown</span>
+            )}
+          </div>
           <div>
             <span className="dim">REVERSE DNS: </span>
             {attacker.ptr_record ? (