Fix JS syntax error: use non-interpolating heredoc for JS block

Perl was interpolating $/ in the regex as input record separator.

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

cpanel/gniza/index.live.cgi

@@ -68,7 +68,7 @@ print qq{  <button type="button" class="btn btn-primary btn-sm" id="next-btn" di
 print qq{</div>\n};
 
 # JavaScript for snapshot loading and navigation
-print <<"END_JS";
+print <<'END_JS';
 <script>
 function gnizaLoadSnapshots() {
     var remote = document.getElementById('remote').value;