erlang: lists keylist BIFs (keyfind/keymember/keydelete/keyreplace/keystore/keytake/keysort) (809/809)

Adds the tuple-keyed list family to lib/erlang/lists-ext.sx: act on
first match, key compare via == (er-equal?), non-tuples/short tuples
pass through. keysort/2 reuses the stable merge sort + full term
order. keytake/3 returns {value, Tuple, Rest} | false. All seven
registered through the er-register-builtin-bifs! wrapper so they
survive mid-run registry resets. lists_ext suite 17 -> 38.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lib/erlang/scoreboard.json

@@ -1,7 +1,7 @@
 {
   "language": "erlang",
-  "total_pass": 788,
-  "total": 788,
+  "total_pass": 809,
+  "total": 809,
   "suites": [
     {"name":"tokenize","pass":62,"total":62,"status":"ok"},
     {"name":"parse","pass":52,"total":52,"status":"ok"},
@@ -15,6 +15,6 @@
     {"name":"ffi","pass":37,"total":37,"status":"ok"},
     {"name":"vm","pass":78,"total":78,"status":"ok"},
     {"name":"send_after","pass":10,"total":10,"status":"ok"},
-    {"name":"lists_ext","pass":17,"total":17,"status":"ok"}
+    {"name":"lists_ext","pass":38,"total":38,"status":"ok"}
   ]
 }