set contest status to pending

Fixed link in `inc/guidelines.pending.hdr`.

Improved link in `inc/rules.open.hdr`.

Updated timestamps and sitemap with `make gen_status gen_sitemap timestamp`.

Changed `bin/status2html.sh` VERSION from "1.4.3 2024-08-05"
to "1.4.4 2024-12-29".

Performed `make quick_www` on macOS to complete the above.

status.json

@@ -1,7 +1,7 @@
 {
     "no_comment" : "mandatory comment: because comments were removed from the original JSON spec",
     "IOCCC_status_version" : "1.0 2024-03-09",
-    "contest_status" : "closed",
-    "news_update" : "2024-12-29T07:03:37+00:00",
-    "status_update" : "2024-12-24T01:52:32+00:00"
+    "contest_status" : "pending",
+    "news_update" : "2024-12-29T09:57:30+00:00",
+    "status_update" : "2024-12-29T10:01:35+00:00"
 }