identity: RFC 7662 full introspection metadata — introspect_full (+9 tests)

introspect_full returns {active, Subject, Client, Scope, Exp, Iat, bearer}
for live tokens and {inactive} otherwise — deepening the opaque-token /
live-lookup model. Access tokens now carry Iat (clock-at-issue); exp = iat +
ttl. Simple introspect is unchanged (all prior suites green). New
tests/introspect.sx. 210/210.

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

lib/identity/scoreboard.json

@@ -1,7 +1,7 @@
 {
   "language": "identity",
-  "total_pass": 201,
-  "total": 201,
+  "total_pass": 210,
+  "total": 210,
   "suites": [
     {"name":"session","pass":11,"total":11,"status":"ok"},
     {"name":"token","pass":24,"total":24,"status":"ok"},
@@ -20,6 +20,7 @@
     {"name":"facade","pass":9,"total":9,"status":"ok"},
     {"name":"delegation","pass":8,"total":8,"status":"ok"},
     {"name":"session-mgmt","pass":8,"total":8,"status":"ok"},
-    {"name":"exchange","pass":8,"total":8,"status":"ok"}
+    {"name":"exchange","pass":8,"total":8,"status":"ok"},
+    {"name":"introspect","pass":9,"total":9,"status":"ok"}
   ]
 }