mod: Ext 7 — repeat-offender escalation (audit log as evidence), 223/223

mod/subject-sanctions counts prior hide/remove/ban decisions about a subject from
the append-only audit log; mod/decide-escalating upgrades a sanction to :ban when
the subject has >= k priors. Non-sanction outcomes (keep/escalate) pass through.
Closes the loop between audit and policy — the trail feeds future decisions. Own
suite. +19 tests.

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

lib/mod/conformance.conf

@@ -15,6 +15,7 @@ PRELOADS=(
   lib/mod/engine.sx
   lib/mod/explain.sx
   lib/mod/severity.sx
+  lib/mod/offenders.sx
   lib/mod/lifecycle.sx
   lib/mod/audit.sx
   lib/mod/api.sx
@@ -32,4 +33,5 @@ SUITES=(
   "link:lib/mod/tests/link.sx:(mod-link-tests-run!)"
   "lint:lib/mod/tests/lint.sx:(mod-lint-tests-run!)"
   "severity:lib/mod/tests/severity.sx:(mod-severity-tests-run!)"
+  "offenders:lib/mod/tests/offenders.sx:(mod-offenders-tests-run!)"
 )