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/scoreboard.md

@@ -1,6 +1,6 @@
 # mod scoreboard
 
-**132 / 132 passing** (0 failure(s)).
+**146 / 146 passing** (0 failure(s)).
 
 | Suite | Passed | Total | Status |
 |-------|--------|-------|--------|
@@ -8,3 +8,4 @@
 | audit | 29 | 29 | ok |
 | escalation | 46 | 46 | ok |
 | fed | 26 | 26 | ok |
+| extensions | 14 | 14 | ok |