mod: Ext 4 — report linking + dedup (Prolog-backed retrieval), 176/176

mod/related-ids and mod/reporters-of find reports about a subject via a Prolog
relational query (report(Id, _, 'subject')) — the policy substrate reused for
retrieval. mod/dedup-reports collapses identical reports by a normalized
reporter|subject|reason key; mod/distinct-reporters-of counts unique reporters.
Own suite (tests/link.sx). +12 tests.

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

lib/mod/conformance.conf

@@ -18,6 +18,7 @@ PRELOADS=(
   lib/mod/audit.sx
   lib/mod/api.sx
   lib/mod/fed.sx
+  lib/mod/link.sx
 )
 
 SUITES=(
@@ -26,4 +27,5 @@ SUITES=(
   "escalation:lib/mod/tests/escalation.sx:(mod-escalation-tests-run!)"
   "fed:lib/mod/tests/fed.sx:(mod-fed-tests-run!)"
   "extensions:lib/mod/tests/extensions.sx:(mod-extensions-tests-run!)"
+  "link:lib/mod/tests/link.sx:(mod-link-tests-run!)"
 )