mod: Ext 1 — negation-as-failure conditions (:not / :attr), 146/146

Report attributes (:attrs) project to attr(Id, name) facts; policy gains (:attr x)
and (:not <cond>) conditions. The Prolog substrate exposes negation as a functor
not(Goal) (the prefix \+ operator doesn't parse here). Closed-world example:
hide spam unless author verified. Default policy untouched — feature proven via
custom rule sets, so all 132 base tests stay green. +14 extension tests.

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

lib/mod/conformance.conf

@@ -24,4 +24,5 @@ SUITES=(
   "audit:lib/mod/tests/audit.sx:(mod-audit-tests-run!)"
   "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!)"
 )