refactor(nip-66): add icon to supported NIPs component for consistent styling

Add FileText icon to RelaySupportedNips Label to match the visual
hierarchy pattern used in other relay detail sections (Performance
Metrics, Characteristics, Requirements, etc.).

src/components/nostr/RelaySupportedNips.tsx

@@ -1,5 +1,6 @@
 import { Label } from "@/components/ui/label";
 import { NIPBadge } from "@/components/NIPBadge";
+import { FileText } from "lucide-react";
 
 interface RelaySupportedNipsProps {
   nips: number[];
@@ -17,7 +18,8 @@ export function RelaySupportedNips({ nips }: RelaySupportedNipsProps) {
 
   return (
     <div className="space-y-2">
-      <Label className="text-muted-foreground">
+      <Label className="flex items-center gap-2 text-muted-foreground">
+        <FileText className="size-4" />
         Supported NIPs ({nips.length})
       </Label>
       <div className="flex flex-wrap gap-1.5">