fix: add User-Agent header to PDF downloads

Some sites (ENISA) reject requests without User-Agent header.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

scripts/ingest-industry-compliance.sh

@@ -124,7 +124,7 @@ download_pdf() {
   fi
 
   log "Downloading: $(basename "$target")"
-  curl $CURL_OPTS -L "$url" -o "$target" 2>/dev/null || {
+  curl $CURL_OPTS -L -A 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7)' "$url" -o "$target" 2>/dev/null || {
     warn "Download failed: $url"
     return 1
   }